You won't be a master per say but intermediate skill is acceptable. If you start out as 'master' where's the room for growth? Also keep in mind healing is a generally unqiue skill. For sake of fairness skill in water bending will be turned down a notch for those who have it. Sort of a checks and balances system. My guy for example. Pro bending earth who specializes heavily in his bending. He lacks most stuff combatants use without it. He also can't see in the ground but in return he has some rather interesting moves in his arsenal.