That’s not a sniper annointment IMO. That seems far more useful on an AR or SMG. It’s the opposite you’d want (bonus damage on enemies above a certain health). Typically, if you’re sniping then you’re shooting at an enemy who is at full health and want them dead in one shot.
Personally, I’d like to see this as the mechanic of a legendary sniper rifle itself, but an anointment to only do health damge and bypass armor and shields would be pretty sweet. Essentially, bring back the Tresspasser. The interesting thing with this is if an enemy doesn’t have a red bar, I could see this weapon/anointment doing no damage 
Another thing I think would be pretty cool is an anointment that returns a certain percent of the damage you do as shields, and the return is doubled if you’re crouched, and even higher if you’re not moving.