You could always take the medium approach. The arm is numb or sore and less effective than before, or perhaps feels "heavy." Probably bad enough to be a severe liability. In time it's probably going to recover with proper care, but perhaps leaves a scar? If they are a battlefield medic, I could see them focusing on restoring functionality asap. But efficacy of healing differs based on the writer. Personally I like to take into account how long the person has bern injured before receiving injury and the relative skill of the healer, as well as other factors such as receptiveness to the magical treatment.
