Roronoa Zoro's latest sword in the "One Piece" series is Enma. Zoro obtained Enma during the Wano Country arc of the story.

Enma is a powerful and legendary sword with unique abilities. It is one of the 21 Great Grade swords in the world of "One Piece" and is renowned for its incredible cutting power. However, Enma is also known to be a cursed sword that drains the Haki and energy of its wielder.

Zoro's acquisition of Enma represents a significant development in his sword collection and his growth as a swordsman. It presents a new challenge for Zoro as he seeks to master the sword's power and overcome its curse. The addition of Enma to Zoro's arsenal further showcases his determination to become the world's greatest swordsman.

Please note that the "One Piece" series is ongoing, and there may have been further developments or changes to Zoro's sword collection beyond my knowledge cutoff. To stay updated on Zoro's latest sword, it is best to follow the official releases of the manga or watch the anime as the story progresses.