Mine definetly is Sparda from Devil May Cry. Especially considering it is the source for the ultimate devil trigger in the (I think it's final) boss battle. Y'know, it's where you fight while flying, and devil trigger is reduced to a single, FF Limit Break esque move that turns you into a dragon and pierce the final bosses chest. Man, that boss rocked. And so did Sparda, I loved turning it into a scythe and throwing it.
And the Nightmare Beta was awesome as well. Fugly, but awesomely kick butt. Could clear a room easily with just that thing.