Simple debunk to all of this copium.
In th One Piece Universe, do you think there was a committee, recognized by everyone in the world like our guiness world records committee, that observed Mihawk, ranked his skill and stuff and compared it to Shanks?
No, the reality is, for whatever reason everyone inside the One Piece verse simply thinks Mihawk is above Shanks.
Something happened to make that a fact, because there is no WSS committee to rate swordsmanship globally lol.
The most likely answer is that Mihawk beat Shanks in their duels while Shanks still had his primary arm, he was left handed in case yall copers weren't aware lol. He always used his left in the flashbacks we see him use his sword in.
So yeah, in the One Piece verse, some event happened that made it CLEAR to the world that Mihawk stands at the top, so stop coping.
And let's not forget, haki is a skill you dunces. Haki is a skill which applies to EVERY COMBAT STYLE at the higher tiers. Haki is not raw power, it is skillfull and technical as well. And what was the first thing Mihawk taught Zoro? Haki. And what did Mihawk say to Zoro?
"Every blade can become the black blade like mine."
So Mihawk shows Zoro haki, tells him with good enough haki any blade can become a permanent black blade.
And who does NOT have a black blade? Shanks. So stop coping, the evidence says Mihawks haki is BETTER since Mihawk has a black blade, which he said is related to haki looool.
EDIT: One more fact from the real world, In HEMA(historical european martial arts, mainly dudes that learn real swordfighting and fight in tournaments and stuff kinda like fencing but more broad) there have been mixed gender tournaments that have been won by women that are way slower and weaker due to a smaller and less muscular frame then their comperitors, and yet their skill made up for it.
Why you ask? Because a sword is a lethality multiplier. You just need to get a touch in with proper technique and aim at the right spots to fuck someone up, assuming they aren't wearing any armor above leather. Meaning that the mens speed advantage wasn't enough with the weight of a blade to compensate for the skill of those particular women.
Of course the stronger men win most often in those tournaments, but the women also did in the past.
My point is just, realistically Mihawk IS stronger AND has at least better armament and observation than Shanks, I can give coc to Shanks since his character moments are all built around it, but even if yall copers are right and Mihawk ONLY has better technical skill in swordsmanship, then given the nature of swordfights, that would still give him the edge over Shanks in a real fight.