In the Prisoner Mine, Luffy wipes out the Pleasures in the sumo ring with ease as he works on repelling his opponents with Busoshoku Haki without touching them, like what Rayleigh did when he first demonstrated the Haki to him.
Armament Haki Rayleigh showed him was really Advanced since he could hit or deflect objects without even touching it.
So it’s confirmed now. Not just Observation Haki but also Armament Haki has its own Advanced stages.
It looks like the Admirals already used Advanced Armament Haki in Marineford when they blocked Whitebeard’s attempt to destroy the execution platform, by creating an invisible shield combination of their three Haki!
So the next stage of Armament Haki might work like some sort of invisible armor that envelopes the user, and also, that might be the secret behind Big Mom and Kaido’s invulnerability.
While Whole Cake Island arc was about Luffy improving his Observation Haki, Wano arc will be about Luffy improving his Armament Haki and acquiring a “suit of armor” to take hits from Kaido. Luffy already jumpstarted the process of training his toughness by training with the seastone cuffs.
Anyway I still think that, even with this armor, Luffy will not be able to defeat 1vs1 Kaido.