So he still has yet to beat a one armed man with a non graded non black blade...
Black Blade or not he couldn't beat Vista and didn't want that smoke. With that black blade he has not went and faced off against Shiryuu with that black blade he did not fight and win against King.
Like i stated his title alone is a gimmick
We dont know what Grade Shanks's blade is. He inherited Roger's techniques and Roger had a Supreme Grade blade. I'd bet money that Gryphon is a supreme grade blade too.
Before we debate Vista, what do you think of Luffy v. Lucci?
His title isnt a Gimmick. He's just an unknown, Oda hasnt revealed a single thing about his combat powers or who he fought & beat except for his Duels with Shanks. That doesnt mean he didnt do anything lol.
Shanks already showed his Signature Technique and Mihawk will 100% surpass it lol.
What if it was one of Rogers weaker techniques
When Oda gave Roger & Shanks the same Signature Technique, he means to tell us that they're fighting style is the same except for the lost arm.
It's like Kaidou/Yamato both using the same Fighting style.