You've mastered the use of Conqueror's Haki, able to use it in a form that infuse your body and weapons with it. This form of haki can destroy just about anything you strike, and even Armament haki is useless against it.

Infusion. Your attacks ignore the haki of creatures who do not possess Conqueror's Haki. If a creature with Conqueror's Haki hits you with an attack, you can use your reaction to make an attack roll against them. If both of your attacks hit, neither of you take the damage and that damage is instead done to all creatures within 100 feet of either of you. Creatures with Conqueror's Haki are immune to this damage.