YouTube #shorts version, about 50ish seconds in length if you want to check it out instead of reading the text: https://www.youtube.com/shorts/ZgD5BRbLnKY (I would embed it here but for some reason it doesn't allow YouTube #shorts)
The text version in case you do not want to watch the video:
To begin, we know there are four grade ranks for swords, Grade, Skillfull, Great Grade, and Supreme Grade swords. For example, Zoro's Wado and Enma are Great Grades, while his Sandai Kitetsu is a Skillful grade.
It is stated that there are 12 Supreme Grade Blades in the world of One Piece, currently, we know four of those swords:
Mihawk's Yoru, Shodai Kitetsu, Roger's Ace, and Whitebeard's Murakomogiri.
However, we also know that turning a blade into a black blade, otherwise known as a Kokuto, increases the grade's rank.
With all that in mind, Since Yoru is a black blade, that would indicate that prior to becoming a black blade, its grade rank was one rank below, which would imply that it was crafted as a Great Grade Sword, and Mihawk forged it into a Supreme Grade blade by turning it into a black blade.
The text version in case you do not want to watch the video:
To begin, we know there are four grade ranks for swords, Grade, Skillfull, Great Grade, and Supreme Grade swords. For example, Zoro's Wado and Enma are Great Grades, while his Sandai Kitetsu is a Skillful grade.
It is stated that there are 12 Supreme Grade Blades in the world of One Piece, currently, we know four of those swords:
Mihawk's Yoru, Shodai Kitetsu, Roger's Ace, and Whitebeard's Murakomogiri.
However, we also know that turning a blade into a black blade, otherwise known as a Kokuto, increases the grade's rank.
With all that in mind, Since Yoru is a black blade, that would indicate that prior to becoming a black blade, its grade rank was one rank below, which would imply that it was crafted as a Great Grade Sword, and Mihawk forged it into a Supreme Grade blade by turning it into a black blade.