[@Holy Soldier] Ah, it looks like we have a bit of a misunderstanding here. I'm not trying to shape him into something I want, I'm just giving suggestions to make him more balanced for the start of the RP, but I see where you are coming from as well. Starting out he would indeed be a bit on the weak side, but right now he has the potential to become grossly powerful incredibly quickly. According to his CS, his physical and mental capabilities are already "above average" and it seems like there isn't a limit to how many abilities he can learn. 

And I would argue that the way you have described his Rapid Cellular Regeneration does essentially make him immortal, as burning every last cell of a person is nearly impossible, which would make the rate at which he can learn new, powerful abilities very fast and essentially risk free. But I now have a better understanding of what you are going for, so instead how about this:

He can regenerate wounds, but if his head is destroyed/decapitated, he his dead as a door nail. That way, there is still a risk associated with him learning new powers and has to be careful when he makes the attempt. I also feel like it would be a too strong if he is capable of retaining the full power of any ability he learns, so perhaps there has to be some kind of storage limit or they are reduced in effectiveness the more he learns.

Again, these are suggestions to bring him more in line with the other players. If you compare him to Karu or Aegis, he would completely invalidate the need for them in any fight as he is now. If you can come up with any tweaks that you like better that levels the playing field, than I am all for it.