I've seen this discussion so many times.
Before I start with my explanation, I want to put extremely clear those things:
- Yes, the sword is his primary weapon and it is utilized in his fighting style
- Yup, haki's level is considered in swordsmanship, but there is a but.
- I'll use videogames combos for Shanks, since he never fought in the manga and also because the games spoiled Adv. CoC since years, with PW3.
So, let's start.
- We know that Shanks is an extremely strong individual in One Piece world, and we know that he started as a member of Roger's pirates.
During sometimes, we know from Ace's novel, databooks, vivrecards and Whitebeard's own words, that Shanks started dueling with Hawkeye and started becoming more famous.
Mihawk was already famous before the death of Roger.
so we know that a not well known Shanks, an apprentice,
fought against the already famous swordsman Mihawk.
So we can already see how much potential Shanks had, dueling during that time against an already not that far from prime, Mihawk.
In fact, Mihawk already had black yoru during Roger's execution.
We also know from Zoro's novel that Shanks is said to be a great swordsman, but he hasn't actually desplayed this great tecnhique with a sword..
We also know that the Shanks who fought against Mihawk wasn't a yonko and he became one after his first meeting with Luffy.
So, what are my conclusions?
I think that it is confirmed that Pre Yonko Shanks was indeed a swordsman, but, as vivrecards confirms he deeply evolved, and only now is a presence equal of that of Whitebeard, he wasn't when he had his duels with Mihawk.
The word used was evolved, so we can assume how much big difference in power there is between a Pre Yonko Shanks and Yonko Shanks, now Mihawk has for sure become stronger too, but he was an already well known swordsman before Roger's death so it's more than fair to assume he didn't evolved as much as his previous rival Red-hair.
But what changed in Shanks?
I think that yeah, he was a swordsman, but.. he has changed his fighting style after he lost his arm and that he started focusing on haki, since we all know that Shanks' forte is haki, his haki is the thing hyped about him.
Yeah, I know, he still relies on his sword, of course he does!
Even Buggy's subordinate was considered a swordsman even though he used various circus tricks:
But you know, being a swordsman doesn't mean utilizing a sword as a primary weapon or anything lke that, it's all based on how you use it.
A sword is used for cutting, and I think that Shanks doesn't do that, just like Roger.
This is how Roger used his sword.
He channels his Adv. COC haki and then throws it with his sword to overwhelm the opponent, but as we could see, Roger didn't do any pierce damage to Oden.
Now I know, Adv. COC can be used for swords too, of course.
But Oden utilized the COC in his sword in a totally different way from Roger, he doesn't just throw haki with his sword, Oden utilizes his haki to imbue his swords, to make them stronger and to do more pierce damage, in fact he even left a scar on Kaido, something that Zoro has done too.
But why hasn't Shanks done that to Kaido? He has a sword and Adv. COC too.
Well, that's because Shanks is just like Roger, his moveset in games is really similar to that of Roger in PW3 and PW4 who came out before we could see Roger's fighting against Whitebeard.
Interesting thing is that in previous games we had the Pre yonko version of Shanks and he doesn't utilize his COC in attacks.
But well, Shanks doesn't focus on cutting and his slashes are totally different from that of Oden and Zoro's, Red-hair just does internal damage like Luffy by throwing his haki from his sword, we known that he has fought Kaido, just like Roger did, so the reason of the Pirate King and Red-hair not leaving a scar must be that.
Maybe you couldn't get what I mean, so I'll post an image to put you in clear the difference between the effect of Roger/Shanks' slash and Oden's one in my opinion, but to put it in clear, Roger and Shanks don't do pierce damage.
This is how I imagine Roger and Shanks doing damage to Kaido:
While COC user swordsman should just leave Kaido some scars like this:
So is Shanks a swordsman? He was one, now he has become like Roger, he can't be just a swordsman as he was before or Oda wouldn't have said that:
That's all from me.