Even though One Piece is a show about piracy and finding the biggest treasure, it also has some of the best swordsmen in manga and animation. Additionally, there are so many swords there that they have their own rating system. There are still many named swords of unknown grades and unrevealed rated swords even after more than a thousand episodes and chapters. Here are the One Piece swords that, to our knowledge, are the strongest.
Wado Ichimonji, Shusui, and Enma, three of Zoro's strongest swords from One Piece
Zoro has been wielding a sword since time immemorial, and he has owned a fair share of them. The strongest of these swords are the Wado Ichimonji, Shusui, and Enma. Wado Ichimonji is Zoro's most treasured weapon as it was been given to him by his master after his childhood friend and greatest rival's untimely death. It's become both a piece of prized equipment and a reminder of their promise to become the strongest swordsman. Wado Ichimonji is one of the 21 Great Grade Swords and is known for its durability and cutting power. It was durable enough to withstand a slash from Dracule Mihawk, while also strong enough to cut Baroque Works' Mr. 1 without being imbued with Haki.
Shusui is the black sword that Zoro inherited after defeating the zombified Ryuma in Thriller Bark. Although it's no longer in his possession, it is still one of the mightiest blades he possessed. It's also one of the 21 Great Grade Swords. and it was also Zoro's sword of choice when using his one-sword-style techniques post-timeskip. Zoro demonstrated its might by cutting a huge galleon after getting into the wrong ship and also by decapitating a dragon at Punk Hazard.
Finally, there's Enma, one of Kozuki Oden's beloved katanas, that Zoro received in exchange for returning Shusui. It's another Great Grade Sword that was able to withstand an attack from Whitebeard, as well as injure the nigh impossible to hurt Kaido. However, what separates Enma from the other swords is its unruliness. It forcefully sucks its wielder's Haki, which can easily take an ordinary person's life. In exchange, the sword is always at full throttle and cuts more than it should. It's also said that turning Enma into a permanent black sword may improve its grade.
Ace and Murakumogiri, two swords of the Supreme Grade
The Supreme Grade Sword is the highest quality of swords in One Piece. There are only 12 of them in existence, and most of them aren't revealed yet. Both Gol D. Roger's Ace and Whitebeard's Murakumogiri belong to this classification. Roger's Ace accompanied the King of Pirates during most of his exploits and withstood continued attacks from same-quality weapons without suffering any kind of damage.
Whitebeard's Murakumogiri is a curious case. Even though it is a Supreme Grade Sword, it takes the form of a naginata instead of a katana. It accompanied Whitebeard during his voyage and also clashed with the greatest weapons like Roger's Ace, Shanks' Gryphon, and both of Oden's blades without any sign of breaking or decay. Murakumogiri is also strong enough to be used in conjunction with Whitebeard's Devil Fruit, which is said to be the strongest among the Paramecia Devil Fruits.
Yoru, Black Sword
Even though Yoru is also a Supreme Grade Sword like Ace and Murakumogiri, it is a cut above the rest of the swords in One Piece. It's a well-known fact that Mihawk's gigantic black sword is the strongest in the franchise. A gentle slash from it can easily cut a ship in two, and a more serious one can send a sharp slash hundreds of meters away as Mihawk demonstrated during the Marineford war. While Yoru's full potential is yet to be shown, it cannot be below any of the above as it was effortlessly able to slice a frozen tsunami.
One Piece is renowned for its expansive worldbuilding, but it's not simply because of how big its world is. It's because the series expounds and fleshes out finer details like the races, swords, Devil Fruits, and even ships. Intermingling these variables makes the series richer and complex. These One Piece swords will naturally play a big role in the looming Final Great War, especially since the Straw Hats' very own Pirate Hunter is also an esteemed swordsman.