These spoilers are tremendous hype.
Zoro has to learn to reel Enma in. This means he's gonna have LOTS of fight time in order to improve his haki mastery.
So Kokuto blades raise the grade of the sword. Interesting, And Enma being the same grade as Shusui suggest it's not a free power up like downplayers claimed. That said, it does possess more POTENTIAL, and it's one Zoro has to realize by training and fighting to make it, or any of his other swords, black.
Luffy casually busting out King Kong Gun with flowing haki!?
I'd like to know the benefits Luffy will gain from this new form of haki in conjunction with G4. Perhaps he can improve the time he stays in G4 or even allow it to where even if he runs out G4's time limit, he can still use haki, meaning no more running away mid fight to replenish your haki.