Noble Titles in Novalis
Duke: Under the Old Imperium, a Dux had been little more than a military commander. Under the New, it referred to the ruler of a province. Even before the Devastation, the term Dux had been corrupted in popular speech to "duke"; afterward, this form of the word was universally used. In Hadron, the title of Dux was more or less hereditary; in Tullia, elected by the prominent families of the province, with the approval of the Emperor. Alaron (and Borea and Cellia, not that it matters any more), had their Duces appointed by the Senate... though they'd been drifting toward hereditary succession for some time.
Thus the Nova Imperium had five Dukes: Those of Tullia, Hadron, Alaron, Borea, and Cellia. (The Emperor was considered to be the Duke of New Aurelia.) Occasionally, the Empire would award the honorary title of Dux of defunct provinces of the Old Empire to those who had greatly benefited the state, but these positions held no real power.
After the Devastation, Leo I, the Dux of Hadron, proclaimed himself King and proposed himself as Emperor. He accepted Alaron as a Duchy Palatine under his own sovereignty. Invoking the old custom of honorary dukedoms, he also appointed Dukes of the extinct provinces of Borea and Cellia, and, optimistically, a new Duke for Tullia. (He reserved the title "Duke of New Aurelia" for himself. Later that title was traditionally granted to the King's eldest son.) Needless to say, Tullia Province did not accept Leo's choice, turning instead to Patriarch Lucis IV, so that title effectively became honorary as well.
These ornamental dukes were eventually granted lands and high precedence within the Kingdom of Hadron, second only to the royal family. Thus, in effect, the title became simply one of nobility; the Dukes of Hadron are the highest peers of the realm. (Their honorary "provinces" are mostly forgotten save by heralds; mostly they're known by the most prominent counties they currently hold.) Over time, several families in Tullia have been given permission by the Patriarchal See to style themselves as Dukes as well.
The unique "Grand Dukes" of Alaron are in a somewhat delicate position - Duke Barto chose the title with great prudence. The title doesn't exactly connote sovereignty, which lets the Hadronese pretend to themselves that Alaron is still in some sense "theirs". (The Grand Dukes carefully avoid other overt displays of sovereignty too, like granting letters patent. There basically are no official lesser nobility in the grand duchy, save those that existed before the split.) Yet it isn't a title granted by the Hadronese crown, either, which suggests independence. This is why the rumors of Grand Duke Vendric planning to declare his realm a Principality are so explosive. ("Prince" is not completely unknown as a sovereign title in Novalis - there's Imperial precedent - but there are no current holders of the title. Generally it's reserved for the children of royalty. Since the Melendrian situation is unusual, and the Patriarch doesn't have kids, this means that so far there's really only Hadronese princes. See "Melendrian titles" below.) Ironically, the net result of all this is that the Grand Dukes have pretty much the exact same precedence they previously had as Dukes Palatine; they were already the highest-ranking dukes in the kingdom.
Marquis: A little-used title, mostly found in Hadron. It refers to those counts of the marches who are granted extra rights and powers to help defend the realm. Hadron has Marquises of Diseirne (for the Loudrush border with Alaron and, more importantly, the Waste), Mondepine (for the Worldspine marches with the dwarves and other less savory beings), Vimarche (for the border with the League), and Verafluche (for the border with the Demesne). (The latter is a bit of a formality, as there's never been a war between Hadron and the Demesne, but you never know. Oh, and the office of Lord High Admiral is treated as the equivalent of a Marquis; the Admiral can authoritatively call on aid from coastal counties. The office isn't hereditary, though. The Hadronese may have issues, but they're not *stupid*.
The March (and County) of Diseirne used to be held by the eldest sons of the Dukes of Alaron. After Alaron's secession, Duke Barto worked out a deal with Leo IX to let his second son take on the title hereditarily, swearing allegiance to the Crown of Hadron. This shrewd move has minimized more than one war between the Kingdom and the Grand Duchy; the Counts (the title Marquis is usually only brought up in military and heraldic contexts) have never forgotten their blood-ties to the Grand Dukes, and relations have been consistently friendly. (The March and the Grand Duchy work together against threats from the Waste, and there've been several intermarriages over the years, too.) Thus reports from the March of Diseirne on Alaronese activity are often rather forgiving, and military expeditions against Alaron are carried out with less than total fervor.
A few prominent noble families in Tullia have adopted the title of Margrave (the Tullian equivalent of Marquis) but there it's purely a formality, granting precedence over mere Counts. One of the League Lords styles himself a Marquis too; since he's the greatest military power in the League, he's been allowed to get away with it. (The Academy - and Visians in general - couldn't care less about such things. To give League titles some semblance of legitimacy in the larger world, the League Lords have established a College of Arms to trace lineages back to Imperial times. This usually suffices to establish someone as a Count. A few League Lords hold Hadronese titles established before secession, too. Most nations find it politic to not raise a fuss about the more questionable League titles, but it's always an option.)
Count: In the Old Empire, a "comes" was an assistant to various Imperial officials. In the New, it became an administrator of a section of a province. In modern Novalis, "Count" is the basic title of nobility. Dukes are rare and exalted, marquises are basically just "counts plus", while barons are small fry, as shall be seen. Counties are the basic division of government throughout Novalis.
When a count is away from home, his heir can act in his name; if a count doesn't yet have an heir, he can appoint someone to fill the role. This individual is given the courtesy title of "viscount", but the position otherwise does not exist in Novalis. (Eldest sons of Marquises are likewise Viscounts. Eldest sons of Dukes are usually given a county of their own to play with. When the duke doesn't have an heir, he appoints a viscount - functionally no different from any other - to oversee those counties.)
In the Demesne, some families prefer the term "Landgrave". Their heirs are still called "Viscounts". (The concept of a viscount is Hadronese in origin, so there wasn't really a Tullian equivalent for the term.)
Baron: Basically, any landholder capable of fielding a band of armed men (or paying the annual equivalent in money - but see below) is a baron. (He might not have the official title yet, but the distinction is rather academic.) This eminently practical consideration arose in the troubled early days of the Nova Imperium, and likewise those after the Devastation. Basically, counts found it easier to co-opt these guys and have them swear allegiance than try to knock them down.
Originally the local count could raise somebody to the rank of baron. Later, this became a privilege of the sovereign. However, the title has never really carried much snoot-value. Barons have Low Justice (and occasionally the High, in a limited way) over their lands, but in the wider world they're small fry. There are, of course, exceptions; barons who wield power and influence beyond what their title would indicate are not unknown. However, those guys tend to end up counts sooner or later.
There's a bit of a movement in Hadron (and to a lesser extent in other places) to tighten baronial standards somewhat, make the title a bit snootier. In particular, wealth embodied in trade rather than land is severely frowned on as a passport to nobility. (It's only in recent decades that such individuals have been growing in power.) You never really could buy the title outright; paying tribute was considered a substitute for supplying a band of men that *you could really field*. Most merchants can't say the same - and mercenaries don't count. Still, some merchant princes have tried buying up land and making a play for nobility that way, and this is what is being resisted.
Knight: Much like barons, knights started out as an eminently practical going concern. A knight was simply someone trained and armed to be effective in war. Owning a warhorse, arms, and armor is not a trivial thing! However, much more than barons, they have been idealized over time. (Perhaps because a wandering knight - they aren't all landed, by any means - can do proportionally a lot more damage than the more closely-watched barons can.) One of the early Leos came up with the idea of establishing orders of knighthood to organize unlanded, unsworn knights, and it proved brilliant. The orders developed a mystique and pride of their own, and this also helped contribute to the exaltation of chivalry. (He may have gotten the idea from Melendor, but sages are unsure. In any case, there are significant differences in how the Hadronese orders are set up. The Melendrian orders were more of a bottom-up thing in origin.) Of course, some of the orders have become powers in the realm in their own right.
The Church isn't entirely comfortable with the ideal of chivalry. The whole "courtly love" thing is only popular at the moment in Hadron, but it obviously has its dangers. And chivalry as a military pursuit has its dangers too. The Church has played up the idea of the "true gentle knight", and has encouraged knights to become Cooperator Guardians, or even full-blown Guardians. (Some communities of Guardians are orders of knighthood in all but name.) Church participation in the creation of the Order of the Flame was something of an experiment, and it seems to be panning out too.
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Ecclesiastical Titles: The Patriarch of the North is of course considered to be a sovereign. In theory, he takes precedence even over the Kings of Hadron, though few patriarchs will press the point. (The messiness of the transfer from New Aurelia to Enmarina muddies the waters, too.) Most of the Leos have graciously conceded it without needing to be pressed, though; the patriarch is everybody's patriarch, even the King's.
Archbishops are formally considered to have rank equal to dukes, and Bishops to counts. Ecclesiastics take precedence over secular lords, with the exception of royal family - though in some cases there are traditional patterns of precedence that hold instead. For example, the few counts who can trace their line back to the Old Imperium sometimes outrank bishops who've been established more recently. It's complicated - that's what you need heralds for. Few ecclesiastics have lands commensurate with their formal title, but some do - usually by royal grant. But usually Church officials are lords on paper; the Archbishop of Leonis assuredly does not hold any real title over the city, for example! (He does have certain rights over a neighboring county, however.)
Ordinary priests are treated on a par with knights. Archpriests formally outrank knights and in practice are treated with more respect than many barons. The position of archpriest carries absolutely no actual power, however - it is purely honorary. Cooperators are usually treated as gentry, regardless of low birth. (High birth still carries its privileges, as always. Though some communities - especially monastic ones - insist that Cooperators and priests give up all claim to worldly power.)
By the way, priests of the Light are not required to be celibate unless the particular community they belong to requires it. Many do, some don't. Virtually all Uniates are celibate, though. And bishops and patriarchs are always chosen from the celibates; it is felt that they need to devote all their energies to their flocks.
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Melendrian Titles: They drive heralds nuts, even though they're simpler than regular Novalian titles.

The trouble is in the precedence - how do you classify these guys?
There's twenty noble houses in Melendor, all descended from the Twenty Who Stood. The Melendrians call them simply Lords. Well and good - they're counts. They fit the bill fine. Trouble is, one of those houses is elevated to the monarchy - and it's not always the same house! Moreover, the two houses that have most recently held the monarchy are accorded some special privileges, since they can't be elected the next time. Custom (one can see the heralds throwing up their hands in disgust) has basically agreed to treat the lords of those two houses as Dukes. Calling them that at court functions in Hadron requires a certain amount of teeth-gritting, which the Melendrians find quite funny. (The more malicious sorts insist on being given *higher* precedence than equivalent Hadronese nobility, since their titles go back to the OLD Imperium!

Likewise the King or Queen of Melendor is considered more or less equal in principle to the King of Hadron, though the Hadronese tone of voice suggests a shade of "less".
Children of the Melendrian crown are in an unusual position, since they are *guaranteed* not to inherit the monarchy. Therefore the heralds have decided that they are not really "princes" and "princesses". They are treated instead as "dukes of the blood royal", who outrank your average duke, but fall behind Hadronese crown princes.
The Melendrian equivalent of barons are called "lairds". (Basically a Melendrian word meaning "lordling".) They're otherwise almost identical to barons elsewhere, except that the noble Lords can create lairds at their whim, and suppress them with the approval of the Crown. (One of the privileges accorded to the "ducal" houses is that they don't need such approval.)
Of course, none of the above titles pass by primogeniture, which is yet another thing to make the Hadronese blow a gasket. For that reason, "viscounts" are quite unknown in Melendor. Sure, a Lord can ask somebody - one of his kids if he wants - to mind the store while he's gone, but it's a much more informal thing. After all, those kids have absolutely no guarantee of inheriting.
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Academy Titles: The mages of the Visian Academy don't give a rat's ass for noble precedence, mostly; they find the whole thing tedious and silly. But heralds make their livings at dissecting the asses of such rats; they have to know what order to introduce people in, after all. The Magister of the Academy is treated as a duke of the lowest possible precdence... even that strikes most Hadronese as too much, but there's something to be said for practicality regarding a guy with the demonstrated ability to defeat your nation in war. Members of the First Circle are treated as counts of the lowest possible precedence. (Also too high in theory, except the First Circle flaunts the right to call hereditary League Lords to heel. Fortunately, most Academicians visiting foreign courts are ambassadors, so their positions are easy to slot in on that basis.)
Otherwise, journeyman mages - Visian or otherwise - are usually treated as gentry, regardless of birth. Master wizards are often treated as the equivalent of knights. (Wizards *were* a military asset in Imperial times!) Confusingly, the usual mode of address for master wizards is "Magister". (Originally the word was simply equivalent to "professor" or "teacher", but confusion with the word "mage" ended up restricting it to wizards.) The guy who runs the Visian League is called "*the* Magister", which gets the point across.
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Protectorate Titles: Another case to give the heralds fits. The two Consuls are plainly sovereigns... but they *share* sovereignty. Thankfully they rarely leave the country! When they do, though, heralds debate on whether they should be treated as equivalent to Kings or Princes. Usage varies... Plebeian Consuls are more likely to be treated as Princes.
Senators are treated as Counts of low precedence. Other Patricians of established lines are treated as barons; upstarts as gentry. Tribunes are treated as gentry. (Though again, any such people visiting Novalis in official capacity are likely to be ambassadors anyway.)
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Others: Folkheim jarls are treated as counts, thanes as barons. The Hoch-Jarl is treated as a King.
Rovers don't send embassies to Novalis. If they did, though, their greatest chieftains would be lucky to be treated as barons.
A Sealord who showed up at a Novalian court would be hanged.

Maybe he'd be interrogated first, but either way it solves the precedence problem neatly.
Tear monks are treated as freemen, ironically enough.
Terrino are mostly treated like scum. They're usually suspected of being criminals, with or without evidence. On the other hand, they've got a lot more freedom of action than your typical serf.
The dwarven Worldspine cities are treated as sovereign nations. Dwarven titles are difficult to piece together, as they never explain themselves. Centuries of precedent have worked out rough equivalents, though the touchy pride of the dwarves sometimes causes issues even now. The Sentinel dwarves are more willing to express themselves in titles humans can readily understand, so they're less of a pain.
There has been very little contact with the elves. It has been decided that the Queen of the Elves is definitely equivalent to a human king. The King of the Elves is a more shadowy figure, though, and there's debate. The majority sentiment is that he'd probably be treated as a king too. Other elves... who the heck knows? In practice, all elves are treated as at least minor nobility, just in case. Elves make much better friends than enemies. Melendrians of course are more in the know about this kind of thing, but they don't talk about it much.
Sirinese Khalifs are treated as royalty, and Sultans as lesser royalty - princes, basically. Other Sirinese titles require more thought. This, again, is what you have heralds for.