The big problem with black blades is that we've known them since day one, we've seen how Zoro performed with one, we've seen how Mihawk performed with one and so far they haven't been impressive at all. And this all probably comes from the fact that "black blade" as in permanently black weapon wasn't a proper concept until very recently; in other words, odds are Mihawk's sword was designed as black just for the sake of his theme since black armament wasn't a thing until post-timeskip (we can apply the same to Ryuma, in fact, who also comes from a "darker" design theme) and even in Dressrosa it didn't feel like Mihawk was talking about black blades in an impressive way ("every blade can be a black blade if you apply haki", basically).
When it comes to actual feats, Shusui was indeed hyped by Zoro as having a higher destructive outcome and hardness, but this wasn't something new: Wado Ichimonji was hyped as the only sword to survive the clash with Mihawk, Sandai Kitetsu was very sharp and bloodthirsty (Zoro had problems to subdue it to his own will) and Enma has been consistently emphasized as somehow special (starting by the fact it can suck haki by itself). And regarding Mihawk, he still required the breath of things to slash a weakling like Bonez, something required with any regular blade.
The picture I get from this is quite messy because Oda hasn't really made the black blades any more salient, any more special than regular swords: Mihawk still needs regular swordsman techniques and his Yoru wouldn't break Wado, and Shusui was just one more sword in Zoro's progress (Sandai was hard to master, Shusui was hard to master, Enma was hard to master). Will Oda retcon this to add new abilities? Who knows, he could follow this path but he could also treat it in a more symbolic, philosophical way; show with it that the swordsman fully connected with the blade; or even make it a proof that the swordsman who left his will permanently in his sword achieved with it the pinnacle of the strongest swordsman, which ultimately is about cutting everything but nothing at the same time.
We will see.
I disagree agree.
We have seen swordsman use black blades but we have seen the full potential of a black blade from a swordsman.
We've never seen Mihawk fight serious once in a manga. While Zoro received a black blade near the end of pre TS but didn't have a chance to master it before the TS. He never got the opportunity to shiw his full potential with a black blade post time skip. He wasn't pushed to his limit prior to the Wano war and Oda took away Zoro's black blade prior to the war. Using them as an example to claim a black blade isn't impressive is not a good example.
Was Mihawk's blade originally designed to be black in color only or just a sword that was created by a blacksmith to have an incredible hard blade. Maybe. Even if was it's not that big of a deal. It's a long manga and Oda has made several changes throughout the manga He has changed haki and even Luffy's DF.
Swords are not DF. They don't give the user new powerful abilities or make them strong just by biting or in this case holding a sword. They are just tools design to help the swordsman grow stronger by them learning to control the sword. Swordsmanship requires hard work but the pay off is huge. That has always been the case. Enma forces swordsman to release more haki then they wish if they can't control it. Zoro doesn't have that power. He can't force other characters to release their haki. He can't absorb other characters haki. Enma didn't give Zoro any new ability. It helped Zoro obtained a new power/skill and reach a higher level by Zoro learning to control the sword.
Regardless of the type of sword a swordsman uses the greatest power for a swordsman remains the same, the Pinnacle of swordsmanship or the power to cut anything or nothing. That power comes from the swordsman. Famous or dangerous swords could help swordsman achieve that power by the swordsman learning to control and master the dangerous or difficult swords. That explains why Mihawk attack didn't cut Das Bones. Unlike Luffy who is still weak against cutting attacks even in G5 mode, Das Bones body is made out of steel so his durability is on Big Mom's level. Cutting Das Bones requires a much stronger attack with greater cutting power. Since his attack wasn't targeting Das Bones body he wasn't cut by it.
The Dressrosa flashback with Mihawk was him hinting at how to create a black blade without straight up tellings him because he didn't want Zoro to learn that way. He wants Zoro to figure it out himself. That's what he told Zoro to go see the world, know himself and grow stronger.
There is no mess when it comes to black blades. Oda just hadn't fully explained everything about black blades. Even when it comes to Black blades the greatest benefit will still come from the user and their power to create or forge a black blade, not from possession one.
Zoro impressed the samurais with a short blade and completely beat and destroy Killer in battle with a scythe, blade or edge weapon he has never even used before, because of his own strength and power with a sword or blade.
One known benefit to possessing a black blade is the blade hardness. Black blades can't be broken. Why is that so important to a swordsman? If a swordsman sword is even broken they have lost the battle. Of course, that is only against strong opponents. A weak opponent wouldn't even be able to break a quality blade. That was the reason Oda had Mihawk break 2 of Zoro's swords with a basic attack. It showed us the difference between a quality blade and a basic blade.
Do I believe that there's more benefits to a black blade then just the hardness of the blade? Yes I do. I talked about that another threat I'm going to post it here:
It's not just about possessing a black blade. The greatest benefit will come from creating (forging) one.
First, there are known benefits to having a black blade regardless how it is obtained.
-blade hardness and greater defensive power. Black blades are unbreakable so possessing one means the user will never have to worry about their sword breaking so their defensive power will increase.
- greater offensive power. Black blades increases AP because of the stronger blade. When Zoro first used shisui his attacks from shisui were stronger than his other swords attacks.
- better haki preservation. Possessing a black blade is like always coating your sword with a strong blackened CoA haki without needing to actually do that. When haki is needed to create stronger offensive or defensive techniques the user won't need to use as much. Of course, black blades don't contain haki so haki will still be needed to counter DF power.
Possible benefits to possessing a black blade.
- I believe black blades are heavy. Creating a black blade increases the weapons weight. Zoro stated Shisui was heavy compared to his other two swords. A heavy blade means the attack will have more weight. That increase in weight will increase the attack power. The user will grow physically stronger from needing to train to control the heavier sword. Shisui my also be a natural heavy sword.
- I believe black blades don't possess cursed/dangerous power. Creating a black blade will remove the curse/dangerous power the sword posseses. I don't have anything to support that but I do find it interesting the only difficulty Zoro had using shisui had to do with possessing a black blade, nothing about shisui.
Let's look at the possible benefits one can obtain from creating (forging) a black blade.
At this time nobody knows how black blades are created but the manga has given us some insight so we have some information to work with.
- largest/strongest CoA haki amount and the best CoA haki control in the manga or near it. There is enough information to confirm blackened haki is needed to create a black blade. But just possessing that isn't enough to create one. Since Zoro has mastered enma he has started to create a green aura around his swords when he's using KoH techniques. We have never seen that before from any character. I believe that is Zoro adding an incredible large amount of controlled blackened haki to his swords and that is the first step to creating a black blade.
- incredible powerful CoC haki and control. We know just to fully master a sword the user must bend the sword to their will. If you create a black blade you aren't just bending it to your will you are changing the sword. That can only be possible if you can completely dominate the sword.
- I'm sure I'm missing one or two more things needed to create black blade.
Of course, a black blade creator will receive a huge increase in CoC strength. Having the skills/power to create a black blade and creating one will make the user stronger. As they grow stronger so will their CoC strength. Similar to what happened to Luffy when he obtained awakening.
