I admit I also enforced a weapon restriction to my characters on one of my 'challenge' play-throughs of the game.

Vaan - Swords, Daggers, Maces
Balthier - Guns, Ninja Swords
Fran - Bows, Crossbows, Ninja Swords, Poles, Maces
Bashe - Greatswords, Swords, Axes & Hammers
Ashe - Swords, Katanas, Crossbows, Staffs & Rods
Penelo - Daggers, Staffs & Rods, Measures, Maces

It made you employ strategy as to which character to use. Making Bashe the only character capable of using greatswords made him very powers, but had little magickal ability (not that magick is very effective offensively). Meanwhile, Penelo is very effective magickally, but her primary physical potential is with the dagger, which isn't the most powerful weapon type. It was quite a nice challenge from what I remember of it.