User blog comment:T- AvatarFan/Is it OP or is it possible?/@comment-24911350-20140607010115

I have to agree with Samjay, Semblances are a manifestation of the soul, and relate to the characters on a deep level. I have to wonder what a character's soul must be like to have a semblance like this. You note that it may have an effect on his mental state, but I can't imagine there's much of one to begin with.

We also really don't know the sort of things about Aura this would require. I doubt RWBY is like Soul Eater and you just have to match "wavelengths". We also don't even know if Aura and Semblance are related, so even if he could somehow match Auras, that may not do a single thing for him. Semblances are also singular abilities while this is two-- The ability to see and analyze Aura on a very base and whole level, and the ability to adjust his own.

It also wouldn't be very useful at all. It would mean his fighting style and weapons would be absolutely incapable of working together with his semblance. He also wouldn't be able to adjust or compensate for new semblances immediately, so he'd be pretty vulnerable for at least the first of half the time he copies it.

On top of all of that, I'm pretty sure it would be against the rules.