User blog:Juracuille/Haoshoku Haki

Haoshoku Haki?
I'm very addle to this, what is Haoshoku Haki? why Ace and Rayleigh no confirmed to be Haoshoku Haki user? they can knock out many men with their haki, what's different with Luffy and shanks? and Rayleigh is able to arrest Kizaru's "Yata no Kagami" to save Strawhats, why?