[quote=Jivusa]
I was thinking about having it be a piece of his soul, maybe half, making him unable to use his soul wavelength much in autonomous combat, but while keeping all of his limbs. If not, then he can lose his arm.
[/quote]

No, it must specifically be a body part. Also, weapons can't use their soul wavelength in combat.

So, his arm is favored? Alright.