Wait you legit have me confused now
Now compare that to Luffy. Luffy learned to use an advanced Form of Armament haki just with instructions. He can do it with or without said sword even so he does NOT specialise in armament haki but King's haki.
Now think about it... Isn't it bizarre that Zoro can suddenly use advanced King's haki in a very special Form for 2 years yet not use "ryuo" Which Oda implies he should have natural Talent for while other people who do in fact specialise in King's haki don't have such forms revealed yet? Like the portrayal is just completely inverted. That is why I am a bit sceptical about ashura being King's haki.