The only situation where I see it being OP is in conjunction with comeback kid(CK) and when you get a bleed on you. The normal hits you get where it does a single heal on you seem like it is just a decent damage reduction talent. So if they could somehow put a timer on how often it could proc, that might fix both issues. Maybe a cooldown on CK where if you didn't get a good heal in time or 3 enemies hit you back to back you would certainly die. Also if there was a cooldown on leech, the bleed would only heal you once and not put you back at full health.
The amount you get healed for might be another balancing issue but it just seems more balanced late game when you are taking more melee damage. Early on the melee seems kind of weak and you get healed for as much if not more than you get hit for. Maybe change the percent it heals for, or change it based on your level and not your health pool.
