After reading the recent chapters of the One Piece manga, I think Nusjuro might just be the strongest swordsman in the world, at least he wouldn’t be weaker than Mihawk. Combined with his long years of life, I was wondering why Nusjuro didn’t have a black blade? This led me to a theory: maybe you need to defeat Death itself to turn your blade forever black.

Zoro saw the Grim Reaper in Wano, it was his chance, but Zoro was weak at that moment and could not even move. In the anime, we saw Death deal its hand and break the rock underneath Zoro, causing him to fall from Onigashima. The only reason Zoro survived is because Franky caught him.

What if, next time Zoro sees Death, he is actually able to move and fight it, defeating it and turning his blade permanently black—a sign of a swordsman who can defeat even Death itself? With Zoro constantly being pushed to the brink of death and that being where he grows the most.

I’ve also wondered why Nusjuro doesn’t have a black blade. No one has ever been able to push Nusjuro to that point? He never had to face Death?

I think it may not be that no one has pushed Nusjuro that far, but rather that Nusjuro is immortal, so a fundamental part of growing as a swordsman doesn’t apply to him. “Death completes a person” but maybe being immortal would prevent Nusjuro from reaching his peak as a swordsman and getting a black blade. That could be the “immortality bad, actually” lesson when it comes to swordsmen.

One more thing, let’s relate it to Haki. Will Power/Haki turns blade temporarily black, so Having Will/Haki so strong that you can even defeat death can turn your blade forever black.