Exsanguinating Blade

+1 to attack and damage rolls made with this weapon. When a 20 is rolled with this weapon against a creature that has blood it gains 1 charge. The dagger can only hold 1 charge. You may use a bonus action to expend 1 charge to: cause you or a creature you touch to recover 2d8 HP, or cause the next creature with blood that you hit to take 2d8 extra necrotic damage.