We’ve been through Fishman Island, Punk Hazard, Dressrosa, Zou and Whole Cake Island… and we have never seen Zoro taken to the limit like Luffy has with Doflamingo, Cracker and Katakuri.
This means that we don’t know how strong Zoro actually is so.. let’s look at it like this: for 2 years Zoro was trained by “The World’s Strongest Swordsman” Dracule Mihawk. Zoro not only learned but mastered how to use Armament Haki but that would not be the only thing he learned.
During the Marineford War Arc when Mihawk wanted to join the fight Boa Hancock stated: “They say the most skilled fighters are struck by fear and are left unable to move when they see those eyes.”
Demons and Spirits play a huge roles when it comes to Top Tier Swordsmen like Zoro’s ability to summon Asura.
Note: Zoro’s eyes glow red when doing illusions
Like I said before the opponents are struck by fear and are left unable to move. This is not Conqueror’s Haki, it’s a Demon based ability which allows the user to create illusions.
Zoro’s Asura being an illusion means that he doesn’t actually have 6 arms and 3 heads, it’s just an illusion which enhances:
Note: this was pre-timeskip.
Other time was the one Hancock was talking about Paralisis Inducement Zoro demonstrated this in his fight with Monet.
Monet a logia user was split unable to reform and you can also see Zoro’s right eye was red.
Let me explain this:
“What’s this?! My body won’t move”
Monet was paralyzed after looking into Zoro’s eyes..due to fear = Fear inducement.
She was cut in half, Zoro did not use Haki. This is where the Art of Illusion kicks in death by illusion.
It’s like this literally convince the brain to copy anything that happens to the victim within the illusion making it possible to kill the target with illusions.
Monet went crazy thinking she was cut in half.
Even when she knew that Zoro didn’t use Haki but she was cut meaning her brain believed that she was cut.
Had Tashigi not interfered by knocking her unconscious it could have killed Monet because there was no way Monet was going to reform if she was concious.
Also why Zoro didn’t finish her off?
I believe that this was what Hancock was talking about.
Mihawk being able to just make people believe that they’re being stabbed by him which drives them insane or eventually kills them even though he’s standing still.
This is most likely the only thing that is on par with Conqueror’s Haki but more rare because it’s a Demon based ability through cursed swords and Zoro and Mihawk are the only known people who are confirmed to use this.
*Theory by King of beasts kaido