Okay so you mention that he has claw arms - which, super cool for one, but are they detachable? Or do they completely replace his regular arms - is he missing them, maybe? Does he repair them himself - if so, who taught him, or was it more by trial and error? Does he have to get someone outside of himself to repair them if they get broken? What are they made of? Does he also repair his own guns - do they malfunction on him?
(I'm not familiar with the anime, but I think I've seen like, the first couple minutes of the first episode?) What else do people think of him? Do some believe that he's cursed instead?
I do love that everyone thinks he's a wizard - that obviously explains the superior tech, right? /s
Does he play it up and spout off random nonsense to explain what he does? Overall I think you've got a pretty decent character concept so far, though!