As pointed out by
@Blazing Lion , they are missing in Dragon Damnation against Sommers.
They are CoA but from my perspective, still a complete mystery.
Brook/Ragnir use the Ice of Hell, IMO, Zoro and Sanji use the Flames of Hell.
Not Haki, but a mystical/magical ability, like Goldenweek's Colors Trap painting (god the Live Action made her a freaking nutcase).
You can at least kind of explain Sanji's "Flames of Love" as latent powers from Judge's human experimentation on his kids. While I don't think it's a Cyborg Power, and it's a natural power that comes from Sanji/Sora, the argument that it is a scientific power is right there, Sanji was genetically manipulated, just like his brothers.
There's no argument there for Zoro, he is a straight country bumpkin swordsmen with no cyborg parts or crap like that, he grew up on a tiny island and does not have any special science powers.
The fact that Zoro can light his sword on fire to begin with is just plain ole magic.
This is another reason V. Nusjuro is his obvious Gorosei fight:
V. Nujsuro clearly uses the Ice of Hell, like Brook, while Zoro uses the Flames of Hell. Since I think the Gorosei fights will be team up fights, with multiple Straw Hats vs each Gorosei, I'd like to see Zoro and Brook vs V. Nusjuro.
I've stated before I thought Elbaph would be an arc with a lot of "magical" powers like Goldenweek's Colors Trap.
It's possible the Flames are Haki based, but, IMO, they're a magical power, and they'll be explored further in Elbaph because it's the "magic" arc.
Edit: Also why Loki is ice based/Zoro tried to attack Loki for pretty much no reason. Zoro's family history regarding Wano is full of Oni slaying, hence Kaido, as well as the Sandai Kitetsu being the 3rd Generation Oni/Ogre Piercer.
Zoro vs Loki is going to be big going forward, we've yet to explore the history of Wano vs Oni, we only touched upon it in Wano.