User blog comment:Kaido King of the Beasts/Chapter 937: Starving for Action (and Shiruko)/@comment-25654036-20190322111027/@comment-2600:1702:3C50:A6E0:60F2:FCCB:6794:4D1A-20190323142111

Zeff did have that nickname didn't he. He did have quite the reputation as a pirate and even after he lost his leg he could still use his replacement when necessary as a form of defense. Not as good as it used to be, but still. Perhaps Ryuma's blade experienced something similar. It would not be the first time I have seen a blade change its composition due to bloodshed. In a manga where I believe Oda was the assistant writer, the author had an antagonist with a blade that became coated in human fat and oils. This coating allowed the blade to ignite into fire from heat generated by friction. Possibilities in imagination are endless.