Okay real talk? All Memes aside? People like Shanks are only referred to as Hakiman by some people in the community to justify Mihawk being the strongest swordsman of the world. Despite Shanks only two combat interaction in the whole series up until now, both involve him using his sword Gryphon. Once clashing with Whitebeard, the other time block Akainu.
Certain people cannot handle the idea that Mihawk despite being a mere Warlord could possibly be stronger than Shanks, and emperor. Thus, they latch on to the only other possible excuse as to why Mihawk is Zoros life goal and hols the WSS title instead of Shanks. Shanks must be a Haki user primarily, and his sword fighting days are irrelevant. The biggest issue is that the further along Zoro progress in the series and the more Haki abilities he begins to unlock and display? The dumber the narrative of Haki and swordsmanship being unrelated gets.
Even if Shanks has his own version of Ashura where he manifests his "spirit" like Zoro can? Zoro is a swordsman. Unless any of the "Shanks is a hakiman" people wanna die on the hill that ZORO of all people isn't a true swordsman? They better learn to accept the concept of Hakiman is stupid. Its the same deal with turning a sword black.
Prior to the reveal of Roger naming his own son after his sword, people dismissed black blade as merely requiring great attachment of the sword in question and being unrelated to Haki. Afterwards? It still gets dismissed as gimmick and not accepted as the clear display of Haki prowess that it is. It's one of the few feats in One piece that is truly unique in its nature because to the best of our knowledge only TWO characters did it. Ryuma, a person infamous for stopping the entire World Government from taking control f Wnao and who's title is literally sword god, and MIhawk. No other feat is that rare. Advance Conquers isn't. Awakening isn't. Both are shown to be more achievable.
Even Oden who has had his metaphorical cock polished during the entirety of Wano was clearly shown to be unable to turn his blades black like Ryuma and Mihawk could. Rogers sword wasn't black. Whitebard, Big mom and Shanks? All bladed weapon users. None turned black.
As far as we know? It's a haki related feat that is truly god tier and almost never replicated. Ryuma lived hundreds of years ago and his blade is still blackened by his Haki to this day. He had such a strong grasp of his Haki and such an immense will that he permanently imbued it into his sword.
That's a god tier feat. So, if we want to be real? Until Shanks turns Gryphon black? The only true Hakimen of the series are Mihawk and Ryuma.