At a guess,based on what ceremonial armor real;ly WAS: lighter, less protective, less restrictive, and FAR more decorated than normal armor.
Scale male made of <i>coins</i> would be one example (and a real-world one, too). The uber-sculpted, gold-and-jewel-encrusted sort of armor you'd expect, say, the King's Footmen to wear might be ceremonial armor -- not REALLY as protective as half-plate (nor as restrictive to movement), but it LOOKS like half-plate, AND it's incredibly-expensive-lookign too.
Ofc, Dungeon 105 may have taken an entirely different route with the concept, in terms of game mechanics. I wouldn't know, I don't subscribe. ^_^