Why can't it be different for GB tbh, it's not like Oda has a rule that he must have all black blade users state their black blades,
Or use it immediately. Especially since Aramaki is based on Gennai Aramaki in Ronin-Gai - it's said that he never used his sword until the end ( correct or not?
@Dragon777 ), and that nobody ever saw him using a sword outside his GF
If that's true, it seems Oda is following that so far with how GB never used his sword in Wano/Mariejois.
Edit : Regardless of everything, he's likely gonna use it eventually. It could still be a black blade by the time he uses it.
A metal black blade ?
Fuji's transition :
As a kid : wooden sword
Adult : metal sword, which just happens to have a wood sheath.
If Oda is applying that transition to GB, then :
Kid : wood club
Adult : metal sword, and since it has hardening without GB using it, it is a metal black blade.
But, i don't give much crap if it's a wood sword coated with permanent hardening
( wooden black blade )
You haven't explained the blackness of the sword, what do you think it is, Hardening or Paint?
What about the Hamon?
Since you throw the sword creation burden on GB, how did he create the hamon?
Did he create it with the traditional way, the so called "differential hardening"?
Or did he create it with this so called "wire brushed" method?
Or with "Chemical Etched" method?
https://www.hanbonforge.com/blog/How-to-distinguish-fake-and-real-Hamon
Or did he create it with a pencil? A pen perhaps?
Or did he create it with brush + paint?
And what is the purpose of Hamon on his wooden sword?
Did he create it just so that it looks like a metal sword? <- if that is true, why did he do that? Is it because he's insecure somehow?