The One Piece Sword God Theory suggests that Zoro's scar is actually a seal that is hiding Ryuma's will which will be his next power up in the story.

Swords like Yoru in One Piece and Murasame in Akame Ga Kill are ... but they were split into two. The Red Scissor Blade was given to Ryouko, and the Purple Scissor Blade was in the possession ...

One Piece's Meito classifies swords into Supreme, Great, Skillful, and Grade Blades based on quality, rarity, and renown. Aside from legendary swords, the series features unique non-sword blades ...