Bleeding Blade

As an action choose 1 weapon that does piercing or slashing damage. You coat the weapon in your blood and it now gives off a faint red glow. You take 1d10 of damage which can not be reduced in any way. The weapon now does 1d4 of extra damage on a hit, and the target must make a constitution saving throw. On a failed save, the target can not recover HP until the end of its next turn. On a successful save, the target can recover HP as normal.