Flaming Haki
The reason why I think now this ability is related to Conqueror’s Haki is because all of the “Advanced Haki users”(Katakuri, Big Mom & Luffy) have it. The color pallet has changed and hardening having an advanced form therefore makes perfect sense. There is Ryou(flowing), which results ultimately in implosions and there is hardening. What would be the application of “hardening”, which is an internal ability with the Conqueror’s Haki? It would be the “flaming pattern”. You are imposing your will onto yourself, which enables you to remain with the properties of your devil fruit while using Haki.
This is why Doflamingo has never encountered this ability before. It’s only useful to people who need to use their devil fruit ability, Haki at the same time and have Conqueror’s Haki. We are taking a real case study “Law” to help illustrate this point. Someone like him would benefit by “Flaming Haki” greatly but he doesn’t have access to it for some reason, even though he knows the normal hardening.
Is it a coincidence that the one guy who is very strong and benefits probably the most on the planet by using the flaming pattern(it enables you to use your devil fruit ability while using your Haki at the same time. It also enables you to apply your devil fruit on the opponent, even if he uses Haki) doesn’t have the Conqueror’s Haki? It’s just perfect for Law and he would be able to apply his devil fruit on his enemy while using his room+sword. Though, he is forced to use an external ability like Ryou around his sword to cut people because he can’t apply his devil fruit with hardening within his blade(hardening changes the properties internally). Only super powerful people like Big Mom, Katakuri and Luffy obtained this stage of hardening. Needless to say, all of them again, Conqueror’s Haki users. To summarize, the color pallet looks something like this.
This entire stage of Haki is separate to swordsmanship and one can create black blades through the usage of Ryou and hardening at the same time.
If you apply this principle of creating a “barrier” around your sword and fill your sword with hardening this process seals the black inside it. This process isn’t important to the theory but just in case people are confused why this isn’t relevant to swordsmanship. The way of the sword is different than the way of the Conqueror and they don’t align.
