This is also my response to everyone saying Soul Eater is a Keyblade.
Uhm, didn't Riku use Soul Eater BEFORE he knew he was the "true Chosen One" in KH1? I'm pretty sure he used that in the battles where he was present before this time and after. I'm pretty sure the kid would've known he was a Keyblade wielder if he'd been using Soul Eater the whole time and it was supposed to be a Keyblade, which it is not. It doesn't even have a Keychain and the design is so foreign to a normal Keyblade type that it's just not all that plausible. =\
Just because it doesn't have a Keychain doesn't mean it can't be/isn't a Keyblade. The ones in the Keyblade Graveyard don't have Keychains either, but they're still Keyblades, and TAV's Keyblades didn't have Keychains until BbS was announced and screenshots were shown, but we still called them Keyblades. And if Riku could use Soul Eater before he knew he was the original person chosen to wield it, he would've been using it on Destiny Islands instead of his wooden sword. And again, he defeats Heartless with it and hearts are released, which only Keyblades can do, so it IS a Keyblade.