But Shuusui is a black blade not one of the supreme grade swords? And if the supreme grade swords are from the void century, how can Enma
become one?
I always thought it depends on the metal that's been used. Cursed swords are made differently or out of a different metal. Maybe the same metal that's been used to build the ancient robots? Did the robots have AI? AI in terms of a soul within them like devil fruits?
I hope Oda doesn't forget to fully explain swords like he forgot ryuuma grave
But Shuusui is a black blade not one of the supreme grade swords?
But that's exactly the crux of the matter.
Saijo O Wazamono Grade
There are twelve Supreme Grade Swords (最上大業物 Saijō Ō Wazamono?).[1] These appear to be the highest-quality swords.
Yoru (Dracule Mihawk)
Shodai Kitetsu (Cursed) (Kitetsu)
Murakumogiri (Edward Newgate)
Ace (Gol D. Roger)
O Wazamono Grade
There are twenty-one Great Grade Swords (大業物 Ō Wazamono?).[1] Their quality is higher than Ryo Wazamono but lower than Saijo O Wazamono.
Nidai Kitetsu (Cursed) (Kotetsu → Tenguyama Hitetsu)
Wado Ichimonji (Shimotsuki Kouzaburou → Kuina → Roronoa Zoro)
Shusui (Ryuma → Roronoa Zoro → Wano Country)
Enma (Shimotsuki Kouzaburou → Kozuki Oden → Kozuki Hiyori → Roronoa Zoro)
Ame no Habakiri (Tenguyama Hitetsu → Kozuki Oden → Kozuki Momonosuke)
We know that turning a sword black allows it to climb the sword ranking. Enma is set among the top 21 by default, and by becoming a black blade, it can even become a Saijo O Wazamono Grade sword.
Shusui is already a black blade, and even though it's a black blade, it's stuck in the top 21 class... This means that before becoming a black blade, Shusui's ranking was much lower. Do you understand now?
We have Enma, which is not a black blade, in the same category as Shusui, a black blade. When Enma becomes a black blade, it will definitely surpass Shusui... If you disregard the fact that Shusui is black and turn it into a regular blade, it can't maintain its position among the top 21 like Enma. Therefore, everything indicates that Shusui was nothing more than a regular blade or one of the top 50 (Ryo Wazamono Grade), which, upon becoming a black blade, jumped to a different 'category' >
O Wazamono.
If Shusui, being a 'bad' sword, experienced a significant boost in reaching the top 21 by becoming a black blade, then the impact of turning a blade black is substantial. This implies that Yoru was initially one of the top 21, and by becoming a black blade, it elevated to being one of the top 12 and the strongest.
Now, consider that the base Yoru, without being black, loses to a Supreme Grade sword (one of the top 12), just as Enma loses to Whitebeard's bisento. If Whitebeard's bisento, which is already considered a Supreme Grade (Saijo O Wazamono) in its base form, becomes a black blade, it easily becomes the strongest blade by far... LMAO
Of course, this assumes that Yoru was initially one of the top 21 swords and that, by becoming a black blade, it moved up a category, thus reaching the pinnacle of the top 12 blades.