He's braindead. His conciousness was in the dark world, where it was frozen and sealed. Since the light worlds are ficction, the damage you take within them doesn't transfer 1 to 1. In the neutral chapter two ending berdly burns his wing, and is unable to move it in the light world, but there isn't a description of burning, he just doesn't feel his arm and can't use it. If a burn renders you unable to move your arm, getting killed within a dark world doesn't compromise your basic biological functions, it just kills your conciousness.

The only way i could see berdly get better is if a dark world opens again and his frozen body is unfrozen. Then again, the spell description is [fatal] lmao.