I always give Fran guns, she looks pretty hot with a gun in Hand.
sometimes i give her and balthier a Katana each and watch them go to town.
I also like leaving Fran weaponless as she does those cool flips.
Balthier: Bow
Ashe: always a massive sword
Basch: the save the queen sword or an axe
Penelo: pole, cos shes a dancer
Vaan: those bomb things or a sword