This goes against my better judgement but I'd kick myself if I didn't at least sign up, I think, so one more entry!! at least
Sorokii Kneaso is the coolest and the strongest and the best 16 year old high school student ever. He's got a really awesome sword and a super hot demon girlfriend, and he'll probably beat you up if you talk trash about either of them.
He was but a normal young boy going to school a year ago, when he made a shady trade: his soul for a cool sword. Though it was supposed to be a piece of junk, something resonated from within the blade and imbued him with fantastic powers! With which he promptly used to kill the shady dealer and get his soul back, since he totally had it coming, man. He did however, lose his arm in the process, but it was super worth it.
The main chunk of his powers comes in the form on his sword, "Supernothing." It pretty much extends to anything you've seen somebody do with a sword, so energy enhanced attacks, shockwaves, boomeranging it, go nuts. To aid this, he has superhuman strength and durability, though by no means is he invincible.
In a fight, he is cocky and mouths off, occasional spouting dumb one liners, then pretty much just tries to sword things as stylishly as he can manage before they die.