Hyogoro attacking the guy with barrier haki is the same thing the admirals,sentomaru and Kuja sisters did!Flow/barrier haki is the same thing:projecting armament haki outside the body to either produce armor,attack with said armor or infuse objects with haki(swords,arrows,bullets,etc...)!Hell,even fodder Kuja island girls could infuse armament haki into their arrows!That is flow/barrier haki!
Basic armament:invisible,allows you to touch logias and improve attack power!
Hardening:visible,does the same thing but increase attack power even more!
Flow/barrier:projecting armament haki outside the body to create a fullbody armor,attack with a haki shield or infuse objects with it!Think of flow/barrier as a external hardening!
Penetration armament haki:a tier above flow/barrier,allows the wielder to project said haki INSIDE things or PEOPLE causing internal destrution!Think of this as radiation(go inside stuff easily)!