Anime has no shortage of incredible sword fighters. Jin (Samurai Champloo) and Afro (Afro Samurai) are among the most spectacular around, but their strength is grounded in realism. Their swords can't split continents, send searing magic through the air or are able to sever the boundaries between realities in order to carve wounds on incorporeal demons.
But there are anime swordsmen and women who can do just that. Zoro from One Piece ranks among the greatest swordsmen in his world, up there with his mentor and rival Mihawk. Saber from Fate/stay night is the master of the legendary sword Excalibur, able to fight even past death. Guts from Berserk is a demon-slaying hulk who wields a sword so soaked in demonic blood it can vanquish evil.
All three reach absurd levels of power, but which one is the strongest sword fighter?
Technical Sword Skill
Each of these three sword fighters use drastically different techniques and styles when fighting with swords. While none of them display the technical mastery of the sword that characters like Kenshin or Afro demonstrate, all of them are masters of the blade.
In terms of technical style, Guts is undoubtedly the least impressive. His whole style is based on sheer, unrelenting strength and power. With his massive sword, it's difficult to wield the blade with much dexterity. Then again, with a sword that massive, speed and power is sometimes all you need. When Guts fought Griffith the first two times in Berserk, he lost the first time because he couldn't match Griffith's technical skill, but won the second time because his strength snapped Griffith's sword. What Guts has that the others don't, however, is a pure ruthlessness and pragmatism in battle, able to do whatever it takes to conquer an opponent, from biting swords to using children as bait.
In regards to Saber and Zoro, however, technique is importnat. Zoro uses a three swords style (or Santoryu), where he holds one sword in each hand and a third in his teeth. By contrast, Saber wields a two-handed longsword. Going on dexterity alone, Zoro clearly has more prowess seeing as how he can use one in his mouth as a lethal weapon. On top of that, Zoro has mastered multiple styles of sword fighting over the years, making him versatile.
However, Saber's whole style incorporates and balances Excalibur's strikes with her prana abilities. Saber is an incredibly talented sword fighter, able to disarm unmatched kendo experts and match the Assassin, an adversary marked by his technical skill, in single combat. Still, Saber probably couldn't beat Assassin if she held Excalibur in her mouth like Zoro. Zoro simply demonstrates more specialist proficiency than Saber. The only issue, for better or worse, is that he has trouble holding back.
Winner: Zoro.
Physical Abilities
Saber's prana augments her abilities but at no point does she demonstrate feats of strength that match either Zoro or Guts. In fact, physically, she's quite frail.
Post-time skip in One Piece, Zoro is capable of blocking strikes from all-powerful entities like Neptune, carve through androids and warships with single strikes, and even defy fields of gravity that should have crushed his entire body by leaping around and spinning. It has come to the point where even when confronted by fighters with greater skill, his raw physical power is able to even the playing field.
Still, Zoro pales in comparison to Guts. Guts regularly wields a sword so dense and heavy that it's actually impossible for a human to properly carry, weighing -- according to fans' calculations -- over 400 lbs! Despite this, he is able to use Dragon Slayer with a great deal of dexterity in battle, moving just as fast as Zoro with far heavier equipment. Guts once carved his way through a literal sea god using nothing more than his sword. An average swing of Dragon Slayer can carve through multiple armored targets at once, as well as demons of titanic size. All this is without the augmentation of the Berserker Armor, which further increases his power.
In addition, while Zoro has endured attacks of intense strength over the years, Guts specializes in just soaking up vast amounts of damage and enduring through it all. He's let himself get stabbed or torn apart just to find an opening to finish off an opponent. In terms of strength and endurance, Guts wins.
Winner: Guts.
Magical Power
This is one area where Guts, yet again, is mostly inept. Guts' Dragon Slayer is bathed in the blood of so many demons it can slice through magical power, but that mainly applies to harming those who are enchanted. The greatest magical ability Guts has is his Berserker Armor, which augments his strength even further, reconstructing his body so he can continue fighting no matter how broken his body becomes.
But Zoro and Saber both have an advantage where magic is concerned. Zoro utilizes Haki to further enhance his abilities. Haki-infused strikes have increased destructive potential, pushing him past all those who come in his way. Most notably, however, is his Kyutoryu style, where his aura manifests like that of the deity Asura, granting him a magical nine swords technique, making him an incredibly deadly adversary.
But Saber's specialty is her magical prana abilities. Using prana, she can augment the strength of Excalibur to absurd levels. She can regenerate her body and defy the laws of gravity. But the key to her power is her ability to utilize Prana Bursts. Prana Bursts greatly increases the force of her strikes, resist magical onslaughts, and tear entire legions of foes to ribbons. Her prana is so great she's able to take on and crush far stronger adversaries like the Berserker using it alone.
Winner: Saber.
Zoro, Guts or Saber: Who is the overall winner?
Every fighter has one area they excel at. Zoro has technique, Guts has strength, while Saber has magical power. But who among them would win in a battle?
All three of them have figured out ways to beat more powerful opponents and more technically skilled fighters in their respective pasts. Zoro, in particular, has encountered so many sword fighters over the years that he's able to find ways to beat just about anyone. While Saber does have a lot of magical powers, she's also unable to keep fights going for long before exhausting herself and, once she's drained, that's it. She's done.
For that reason, it's likely Saber would be the first to fall, leaving Zoro and Guts left. While Zoro does have a great deal of skill, Zoro isn't unstoppable. The key thing will ultimately be this: while Zoro has greater technique, he's never faced an opponent as unrelenting and violent as Guts. Guts does whatever it takes to win. While Zoro might be physically weaker than Guts, he'd be able to hold Guts off with pure technique and Haki-infused strength.
In addition, while Guts has taken a great deal of punishment in his days, so has Zoro. Both Guts and Zoro have had their limbs cut, their organs split open, had saws plowed through his body, and so on. However, unlike Guts, Zoro's Haki can be used to re-shape his endurance. Ultimately, while the fight would be brutal and long, Zoro would emerge on top.
The ultimate anime sword fighter is... Roronoa Zoro.