Did Oda ever refer to Shusui as a red blade? A black & red blade?
You gotta get real here lmfao, these are garbage arguments.
You're inserting something into the story that, to date, does not exist in the story. A story that contains 1000+ chapters and plenty of swords.
I'll applaud your imagination but that doesn't make your argument Pre-anime reveal valid.
I've said a few times, especially since entering the discussion today, his blade isn't black. The anime preview showed that and unless any corrections come out like with King's wings, it's not black.
I'm harping on people who are patting themselves on the back for calling it when, prior to this, they were arguing against blatant evidence.