Considering how this artifact of doom is created (forged from hearts of living beings), its implied tremendous power and providing access to the ultimate power in form of the true Kingdom Hearts, no one should wield the damn thing.
Ventus had his heart nearly destroyed and went into a ten-year coma because of that stupid thing, not to mention all the other lives Xehanort messed up because of it.
Heck, the whole universe was once destroyed in the first Keyblade War because people wanted to wield this damn thing.
(Not to mention that its extremely ugly, but that's just a personal impression).