Zoro has been downgraded with his COA as Wano shows as if it didn't stop him from fainting and handling blows
I don't think there's any indication we've seen in any previous arc to back up the claim you're making that Zoro's CoA has been "downgraded", so unless you can provide a ref from a previous arc and let me know what current scene you're comparing it to...
Zoro didn't use haki against Kamazou, so it wouldn't factor in him fainting. And what are these blows that you're talking about, you mean the nails again or being slashed by Apoo or...? Was he also using haki there? I asked you this before but you didn't answer, does incurring damage equal defeat? Because Zoro fighting with a bladed weapon means he's likely to incur significantly more damage than your average fighter but also the way his character is portrayed, it's essentially a staple in most of his fights. Pre-timeskip anyway.
Here is the Zoro v Kamazou page for reference so you can answer me.
Gyukimaru pounces, Zoro evades, almost immediately Kamazou swings at Zoro and wounds his upper chest.
Vergo just destroy him given his more flexibility with Haki is better than Zoro's who doesn't have time to react and need to charge his Haki before use.
You're right, Vergo being a rokushiki user means he could use his haki in a number of ways( full body cladding, strengthening his rankyaku, shigan, etc), but that in no way proves it's stronger than Zoro, but I accept this is merely your opinion on the matter. Zoro being a swordsman means he would have little use to clad his legs (for example) in haki during a battle. Unless you're saying Vergo can break Zoro's swords while imbued in haki?
What do you mean by charging his haki? haki depletion would happen the same way for every character, surely if Zoro has to "charge" his haki, the same would be said of Vergo, in which case that would leave him even more vulnerable to Zoro's attacks, no?