Here’s a theory I haven’t seen much discussion about: What if Devil Fruit users are weak to water because someone stored their haki in it?

To start, I initially thought that Sea Prism Stone was metal permanently clad in haki—kind of like how black blades are formed. Maybe a combination of Conqueror’s and Armament Haki is involved in creating it, but let’s explore that idea further.

Haki Stored in Water

Chapter 1122 Spoilers reveal a knot inside Emet that was created by Joyboy. This got me thinking: What if someone applied their haki to water the same way they did with the knot?

While haki normally doesn’t drain a person’s strength, there might be exceptions for applied forms of Conqueror’s Haki. We’ve already seen how Conqueror’s Haki can paralyze others or make them completely powerless, similar to how Shanks made Green Bull practically useless just by exerting his haki from a distance.

Now, if sea water contained stored haki, this could explain why it weakens Devil Fruit users. In this theory, the sea’s effect on them would be like a constant, passive form of haki that strips them of their power—much like how Shanks made Green Bull retreat or how the Gorosei lost their transformation once the knot was opened.

Linking Sea Prism Stone to Haki

If this theory holds up, Sea Prism Stone could be similar to water but in a more concentrated form. Maybe it’s a material that has been permanently infused with haki, similar to how a black blade is permanently imbued with haki by its wielder. If water can store haki in some way, it would make sense why both sea water and Sea Prism Stone have a similar weakening effect on Devil Fruit users.

In short, haki stored in water—perhaps in a form akin to Conqueror’s Haki—could be the true reason why the ocean and Sea Prism Stone make Devil Fruit users powerless.