I don't think he is Yonko level....He himself said at the War of Marineford that "I want to see how much is the difference between me and the one they call the world's strongest." Fighting 1vs1 with Shanks is incredible but we don't even know what kind of fights were those or what was Shanks level at that time..Shanks lost his arm a few years back...if he was Yonko level back then I am surprised that he didn't use armament Haki to save his arm although it seems like he did use Conqueror's Haki to drive away the monster...Also his presence at the Marineford and the ease with which he stopped Akainu make sme think he is stronger than Mihawk....Mihawk's swordplay is the greatest and Shanks rivaled him in his forte...combine it with Conqueror's Haki to the extent that Whitebeard called it impressive is surely a big deal...
Well he's the same guy who enters Shanks' territory with no care in the world. He told the weakling to point where is shanks. He entered the cave with Shanks' top tier members like Benn Beckman , Yasop etc