Blood Draining

Permanently enchants your weapon to sometimes grant Blood Reserve when striking an enemy or inflicting damage with bleed attacks. When you fall below 35% health, Blood Reserve restores 180 to 219 health. Lasts 20 sec and stacks up to 5 times. This enchantment requires the wielder is at least level 75.

Source
Taught by Formula: Enchant Weapon - Blood Draining.