Oddly enough I was going to ask this yesterday after the Witches' Forest Arc but was doubtful since I was only at that part in the manga and my question might have been a little theoretical since I didn't know the full extent of the emperor's magic.
But now after the Royal Knights Arc we see the magic emperor himself face off against Licht and he uses his magic to reverse the flow of time and heal himself.
My question is why couldn't or why didn't he do the same for Asta's cursed arms or Fuegoleon's entire arm? We know he can restrict the flow of time in a specific area, why isn't he the greatest healer in a sense of should being able to revert a body to its previous state?
