Can Zoro Use Haki. The WSS is akin to owning your own small business and the Pirate King ambition is like the CEO of a multiple billion dollar enterprise the second to the CEO is the COO and thats the role Zororayleigh and katakuri plays. So losing sight might be A KEY to AWAKEN ultimate Swordsman powers.
So if Zoro didnt awaken his Conquerors Haki yet or havent used it in any form theres no way for them to know he has it not even Mihawk. That doesnt mean asura IS the manifestation of conquerors haki it just means Zoro subconsciously coated the attack with it. Though she has not yet displayed the ability to use Haki Robin is fully aware of the power as she commented on Luffy knocking out half of Hodys men.
Zoro does have control over some Haki abilities.
He was first noted to have used it by Kaido after the Emperor was struck by Zoros Kyutoryu attack. In the last chapter 1010 Kaido literally said that Zoro has conquerors haki which is manifest in his ashura form. And when Tashigi asks wether he used Haki or not Zoro does not even bother answering. Unlike Armament or Observation which is already latent in all living creatures.