I wanted to discuss a possibility in verse why notable and powerful pirates did not show Haki pre timeskip.
Yes out of universe I’m aware it’s because Oda did not think of the Haki system or want to utilize it at the time we met these pirates, but in universe I believe there’s a reason why certain pirates didn’t show Haki when we fought them and why they may show it again in a reintroduction to their character. So I’d like to focus on Gecko Moriah and Crocodile.
So why do I think it’s possible that Haki can be loss.
First, let’s consider what Haki is. Haki is quite literally willpower. All of it is dependent on your will and this will grants you insane abilities through the three colors.
However; what happens if a pirate loses their will? What happens when their confidence in themselves is broken? This I believe is what triggers a weakening and inevitable loss of Haki.
Let’s consider Crocodile and Moria’s shared past. Both characters fought against Emperors and loss badly. Moria lost his entire crew, and Crocodile lost something himself and because of these losses they looked for outside help to achieve their dreams. They no longer thought their dreams were possible through their own power and this is where I believe their Haki started disappearing.
Moria decided to replace his own power with an army of undying Zombies and Crocodile decided to replace his with an Ancient Weapon. Neither of these two decided to strengthen themselves and because of this they lost the ability to weaponize a will they lost.
So what does this mean next time we’ll see them? We saw Crocodile regain his will in Marineford; if we see him again, he may very well regain his Haki.
Moria is currently with Blackbeard and it’s possible that next time we meet him, his Haki will return as his entire crew is gone and he’s left alone.
*Theory by GreenLanturn73