Is there a way to get rid of it? It also appears to be a category of its own.

It is not classified as a sickness, so faith healing etc. does not work.
It is also not classified as a disability, so sorcery does not work either.
It is also not a stress effect.

It makes sense that mortal knights can get wounded and even permanently crippled in combat. All of the other bad outcomes of war and botched medical treatments, like losing a leg, blindness etc. can be cured by supernatural healing powers. Is this one exception intentional?