What we know about Haki right now is literally just the basics. Basics of Observation Haki, Armament Haki and Conqueror’s Haki.
As we go along we learn a little more about it. I think there’s going to be a next step in Haki involving elements. I’d say there’s been foreshadowing but really that’d be underselling it this is rock solid evidence. Allow me to give examples of Elemental control seen in the story.
Luffy’s Red Hawk
Sabo’s Dragon Fist Breath
The New World Pirate McGuy
Brook’s Ice Attacks
So basically we’ve seen multiple characters use Elements in their attacks. Sabo who had no devil fruit seemingly used the force of his Haki or wind to destroy the coliseum ring. The move ended with the word “Breath” tho which makes me think Sabo created wind.
Luffy’s Red Hawk is my biggest example for this theory. With just the addition of Haki he was able to use fire literally out of no where and it’s clearly not from just the Armament because if so Luffy would always be on fire when his Armament is up. I believe fighters can master a form of nature with Haki. Different fighters have different Elements that are a representation of that person’s spirit or personality. Then you “will” that element into existence because that’s all Haki is will power or your spirits power same thing. Luffy made fire under water so he clearly willed that flame into existence.
We’ve seen McGuy used lightning and we know he doesn’t have the lightning devil fruit. Luffy’s fire, Sanji’s fire, Sabo’s wind and even Zoro used fire against Ryuma. So there’s loads of people in the story using Elemental powers with no explanation like at all.
This being a next step in Haki would answer so many questions. As well as add new ones like what determines your element? I believe Sabo’s may have became wind because of Dragon. Possibly Dragon trained him to use wind with his haki. The 2nd question would be, can you learn more than 1 element?
What’s even weirder about this element theory is that the Monster Trio all have fire as their current element. Maybe people with similar spirits have an affinity towards the same element. Maybe being around people with the same element just has it rub off on you who knows? Well Oda knows but he’s stingy with sharing info. Maybe you can have more than one element too but we’ll have to see about that.
*Theory by RomanceDawn