I also love how they use characters from the past to claim that Mihawk is superior simply because he has a black blade. Since it's never stated that this is a feat of strength, it could simply be a connection to the sword or excessive training. Remember, Dembele or Raphinha could be chosen as the best in the world this season; that doesn't mean they're on the same level as Messi.
This isn't a good argument since Oden's dad say this about Emma raised rank if it's a black blade
To tame Enma u gotta control your haki/Ryou, even a swordsman with pretty good Haki/Ryou user like Kinemon are scared to use it.
And to use Enma freely like Oden's did, you gotta release your haki fully not restrict it.
And even after Zoro unlocking CoC and Oden's constantly using CoC to use Enma, it's still not yet "Forged". The term " Forged" So far the only hints that u gotta had countless of battle using the sword.
That means if the sword are gonna raise the rank because of black blade especially to Saijo, that Sword is gonna be a lot stronger than before. If the sword get stronger, automatically the user is also getting stronger. Either haki or his swordsplay.
Thats a feat of strength