I don't really care one way or the other, but great thread!
We're bound to see more black blades/Supreme Grade swords now that we're approaching EoS.
Even if GB is overpowered, he'll go down because he's hot-headed and does things on his own behind the boss's back, motivated by personal glory. He could have a black blade, awakening, CoC, whatever-- but his weakness will be his decision-making.