Skill - Healing.

To heal a wound your character would need to know the make up on the body tyupe it was healing for example if you didn't know how the muscle you were healing should re-conect to the severed side to which you are joining it, but you still went ahead with the healing the muscle would most likely not be joined bac kup correctly and therefore would not function correctly, this in mind there a very few who can heal a wide range of creatures.
physical healing is generally the saturation of the remaining cells of whom' you are trying to heal with your own or other energies to promote accelerated Cell reproduction in the area of which has been damaged, though in extreams healing can be used to heal mental disoreders in other characters.
If healing is used to its upmost capabillity it can also be used as a weapon.

( Pm me if you see any issues with this explaination, and i'll try fix it to the best of my abillity.)