Roland Delacroix said:
You know I was thinking the same thing a few days ago but it just hit me that this is perfect for one fo my players. He wants to do the Final Fantasy thing wielding a sword the size of many small nations. I'll have to tell him this is the way to do it.
Although I do see a certain coolness factor in carrying around a massive sword, it should carry certain disadvantages.
First, it marks the character as extremely distinctive, which many gamers like, but really works against the character whenever he wants any measure of discretion or anonymity. "Have you seen a guy with a huge sword?" "Yup, couldn't possibly miss him."
A sword like that also marks the character as a trouble maker, in the eyes of any peacekeepers. Imagine you're pulling watch duty for some city and the guy coming up has a gigantic sword strapped across his back. Do you let him into the city? I sure wouldn't (or at least, he'd have to leave the sword with the guards).
A sword that's too big is extremely unwieldy, aside from the weight factor. It's an encumbrance issue. In the Rurouni Kenshin anime series, there was a character (Sanosuke) who used one of those giant swords. The hero, Kenshin, found it incredibly easy to anticipate how the other guy was going to strike, because with a sword that size (wielded by a human size character), there are only two ways to attack: either a horizontal strike, parallel to the ground, or a vertical strike, swinging downward at the target. So even if the weapon had the stats of a large weapon, I'd still give it attack penalties when used by a medium size character.
A really big sword is also going to be impossible to use in confined spaces, including many dungeons and other indoor areas.
On the plus side, a really big sword should give a circumstantial bonus to Intimidation checks.
But hey, you're the DM, and if a sword like that is cool with you, it's up to you whether or not the character faces any consequences of his weapon of choice. I'm all for making PCs unique, but I also prefer a degree of realism.