I went and looked up some synonyms for "Blade" and "Knife."
I almost went with Souledge until I realized, well, that's a videogame.
Soulscythe sounded cool, but I think that ends up with more implications than I intended.
Soulshank was hilarious for several reasons. (One of which is that it should have been Soulshiv in this context, which is what I'm officially calling my Mind/Soul blade from now on).
Soulsabre was kinda neat.
Soultickler? What?
That aside, I've changed the class so that it cannot be True Neutral. I've additionally considered adding the benefits of wielding a Soulbound Weapon into the relevant chakra binds for the soul blade... minor benefits, and would make sense I think.