Maybe not the genre you were hoping for but I'll throw in dark cloud.
The weapons in that game are sort of like pokemon because they level up, gain abilities, etc. They can also be merged to combine abilities and if they reach a certain level they evolve into a different form with even more new abilities. It's one of, if not THE, best aspects of the game. There's even one that talks...
One could even argue the game is all about the weapon customization because the characters themselves are only as strong as their weapon. Besides hp and defence they have no stats of their own, it's all on the weapons.
Weapon variation is also pretty good because each character (there's 6) uses a different kind: swords, hammers, polearms, catapults, magic and machineguns (yes, you read that right).
There's alo a sequel: dark cloud 2 (or dark chronicle in Europe) which I never played but I assume it has similar weapon customization. (feel free to correct me if I'm wrong)
I can't guarantee you'll like the rest of the game though... It's a little childish and smells faintly of JRPG.