Roronoa Zoro is the combatant of the Straw Hat crew and one of the strongest swordsmen in the entire One Piece series. He is a master of the Three-Sword Style and thus, wields three blades at once, one in each hand and one in his mouth.
Although Zoro started from the very bottom he never stopped working hard and, with time, he got better and became capable of wielding some powerful swords. Over the years, Zoro has wielded some of the strongest named blades, with some being regarded greatly enough to be treasured.
5 Sandai Kitetsu
Sandai Kitetsu is one of the great swords that Zoro wields currently. Out of all the named swords that Zoro has ever wielded, the Sandai Kitetsu is known to be the lowest-ranked of them all. This sword is cursed, however, which makes up for its low-rank, in a way. Sandai Kitetsu was forged by Tenguyama Hitetsu, one of Wano Country's top swordsmiths.
As with all other Kitetsu blades, this one is known to be cursed as well and it is said that whoever wields it dies a terrible death. That, however, isn't always the case as its curse can be conquered. Zoro managed to bring it under his control with relative ease, though he mentioned that it was difficult to keep its bloodlust in check at times.
4 Yubashiri
Yubashiri is one of the Ryo Wazamono grade swords, which makes it one of the best blades that Zoro has ever handled. This blade was a gift to Zoro by Ipponmatsu, a sword seller in Logue Town. Upon testing his luck against Sandai Kitetsu and surviving, Ipponmatsu gave the Yubashiri to Zoro free of charge.
This sword was described as being quite light and sharp by Zoro, which was more to his liking. It struck swiftly and was much easier to control than the Sandai Kitetsu, known to be cursed. Zoro's control over the sword got better with time. However, this blade ended up dying at the hands of Marine Captain Shu at Enies Lobby, who held the worst power any swordsman would want to face: The Rust Rust Fruit. The remains of Yubashiri were put to rest by Zoro on Thriller Bark, which had soil from the West Blue.
3 Wado Ichimonji
Wado Ichimonji is a Meito that belongs to the 21 O Wazamono grade swords and were forged by the legendary swordsmith, Shimotsuki Kozaburou. This blade once belonged to Koushiro and was supposed to be given to Kuina. Unfortunately, Kuina died, but to keep his promise to her, Zoro took the blade for himself. This blade is one of Zoro's most precious treasures and one that he will never switch for any other blade.
The Wado Ichimonji is quite a special blade and has been through countless battles so far. It has managed to block attacks from black blades such as Shusui and even one of the Saijo O Wazamono grade swords in Yoru. As with any blade, Wado Ichimonji's rank can also rise if it is successfully turned into a black blade over time by constant imbuement of Armament Haki.
2 Shusui
Shusui is considered to be a legendary blade that was once wielded by the Sword God Shimotsuki Ryuma of Wano Country. After his death, his blade likely marked his grave in Ringo and some time ago, Gecko Moria stole his corpse and his blade for Zombification. Shusui was successfully turned into a black blade by Ryuma and had already peaked as a blade.
Ranking among the 21 O Wazamono grade swords, Shusui is incredibly powerful and especially known for its durability and toughness. According to Zoro, this blade wouldn't bend a millimeter even if a dinosaur stepped on it. Zoro wielded it for quite a while, however, it was ultimately returned to Wano— and in exchange, Zoro got a sword equally as good, if not better, in Enma.
1 Enma
Enma is a legendary blade that, just like Wado Ichimonji, was crafted by none other than Shimotsuki Kozaburou. This blade is also one of the 21 O Wazamono grade swords and that's one of the many reasons as to why it is considered to be special. Long ago, this sword was wielded by Kozuki Oden, Wano's strongest Samurai. However, before his death, it was passed on to Hiyori, while Ame no Habakiri was to be passed on to Momonosuke.
20 years later, Hiyori passed on Enma to Zoro in exchange for Wano's treasure, Shusui. This sword made Zoro much stronger because of its special ability to draw excessive Ryou from his body and the fact that Oden's spirit seems to reside in it. As such, this sword is a massive power-up for him as it improves his control over Ryou and allows him to use more than a regular blade would. In the future, Enma could potentially be turned into a black blade as well, just as Hitetsu said to Zoro.