It's just high concentrations of haki, not some new special different haki...
As I said, his legs were never a fundamental part of the transformation, it has always been an optional thing since day one, can the same be said for his upper body? No, that has always been a requirement until Elbaf. Here Luffy is turning only a single arm into G4, that's vastly different from anything we've ever seen before.
So your argument is just baselessly assuming he could do it the entire time but just never did for some reason... what a great argument.
As I said, his legs were never a fundamental part of the transformation, it has always been an optional thing since day one, can the same be said for his upper body? No, that has always been a requirement until Elbaf. Here Luffy is turning only a single arm into G4, that's vastly different from anything we've ever seen before.
So your argument is just baselessly assuming he could do it the entire time but just never did for some reason... what a great argument.
I guess Nami can't use her cloud road with Zeus since she didn't demonstrate it. Loooooooool