That concept of Haki storing makes sense, obviously it doesn't diminish Zoro as one of the heroes because Enma is but a channel for Zoro to learn basics of permanent black blade.
But Zoro would surpass Oden regardless, because it is literally a foregone conclusion at this point that he is surpassing Odens best feat against Kaido.
Zoro is already Oden level in most stats like physical strength, AP, DC, lethality, endurance etc.
But Zoro would surpass Oden regardless, because it is literally a foregone conclusion at this point that he is surpassing Odens best feat against Kaido.
Zoro is already Oden level in most stats like physical strength, AP, DC, lethality, endurance etc.
Onimaru tells us Shusui was "Forged" into a Black Blade through Ryuma's "History of Battle." It's not something he just pulled off one day out of the Blue because his Haki became strong enough. The Sword itself was "Forged through battle" which is a process. Forging something is not a one step method.
Armament Haki itself is literally the process of "Hardening". So it stands to reason that through continuous hardening of a Blade, the blade itself is being "Forged" into a harder substance, until it eventually permanently turns black. The fact that it turns black is what symbolises that the blade itself has now become a higher quality blade, as the hardness of the blade it what it's quality is based off of.
Hitetsu states that "Enma is not yet forged into a Black Blade." This implies that the process has already begun. I doubt Oden wasn't capable of turning Enma black, rather that he died before he could achieve it.
If Zoro turns Enma black, and it was partially attributed to Oden, it doesn't diminish Zoro in any way. Because through that, he will learn how the process of turning a blade black works, and will be capable of turning Wado into a black blade in not even a fraction of the time Oden spent with Enma. That is a clear indicator right there that Zoro's growth and potential, far surpasses that of Oden.