Cursed swords were first mentioned in chapter 97 when Zoro saw the Sandai Kitetsu, one of the 3 cursed Kitetsu blades. According to the story, many famous sword suffered tragic death after carrying around the Kitetsu blades.
But even with that story, we haven’t actually seen anyone who is really being cursed by a sword right? Although there is Cavendish with his dual personality Hakuba which could be a result of being cursed by his sword Durandal and there is also Law with another cursed sword Kikoku, but there isn’t any specific info that says they are indeed being cursed. Then after hundreds of chapters, another Kitetsu blade has been introduced, the Nidai Kitetsu which Luffy got a hold onto.
So I thought that the perfect time for Oda to finally introduce a cursed swordsman is now in Wano.
The question is who would it be?
Well, the first person that came to my mind is King The Wildfire which many people speculate will be Zoro’s main enemy in Wano.
At first the idea of him being cursed just came out of nowhere but further thinking about King, I remember that this dude is emitting flames from which I firstly thought to be because of his devil fruit ability. But that doesn’t seem to be the case, his devil fruit is the dinosaur Pteranodon which doesn’t have any connection with flames.
So what is the source of his flames? Well I think it is because of the curse of his sword. I believe that curses manifest in different forms and the curse of King’s sword is that anyone who touches it will be burned and engulfed with flames.This could be the reason why King have his body completely covered, to hide his burned skin.
But how did King get affected by the cursed and how is he still alive even being engulfed with flames? I think the first time King touched the cursed sword, his state of mind is very weak but as the time passed he managed to create an immunity to the cursed swords flames by strengthening his “will”.
*Theory by jinz