Sabi Sabi no Mi in One Piece

As the fruit hasn't yet been shown in the anime, we don't know a lot about its appearance.

The major strength of this fruit is that it is able to rust and pull apart metallic weapons such as swords. This gives the user an advantage over swordsmen. The fruit also gives the user the power to have a permanent defense against swords or any metal objects. If the sword touches the user's body then it automatically rusts and falls apart. The fruit's power can also affect the user's body.

One weakness of this fruit is that, if a living being is affected by the rusting effect then the technique would be reversible as they're not oxidized completely. Other than that they have the standard devil fruit weakness, that is the inability to swim.

We can see Shu using his devil fruit powers for defense and offensive purposes. He used his devil fruit power to rust one of Zoro’s swords by catching it in his bare hands. He was able to break the sword as if it was nothing.

Q. Can Shu use his devil fruit powers on living beings?

A. Yes, Shu can use his devil fruit powers on human beings too.

Q. Who ate the Sabi Sabi no Mi?

A. Shu ate the Sabi Sabi no Mi.