Nothingness
Two Thousand Club
By theory, if the character has a lack of feeling any form of pain or simply high tolerance for it...the limb will still regrow on its own. Although it is still a fact to remember that the limb is not protected by the user's aura due to it being of Grimm.So theoretically, could the lack of having pain sensory or just a high tolerance make it less likely for a Grimm take over? Or is it the pain and extreme emotion held with the pain that makes the Grimm regen it?
Although yes, it does mean it is less likely that the Grimm will take control since the pain practically won't be there for the user so the focus won't be on it and the emotional feelings attached to it most likely won't be present with it as well.