The world of One Piece is filled with characters with unique abilities, largely because of the existence of Devil Fruits. There are characters who can manifest operation rooms at will, inject hormones and even some who can manipulate souls. The Straw Hat Pirates aren't unfamiliar with the concept either. The crew itself is a cacophony of curious beings with various ambitions and distinct abilities. Even among them, their resident musician is a special case.
Brook's Devil Fruit, the Revive-Revive Fruit, granted the music-loving pirate a second chance at life. And alongside his soul returning to what remained of his body are some interesting -- and weird -- abilities. Here are the weirdest among them.
Bone Regeneration from Drinking Milk
Brook, in a sense, is immortal. He won't return to the dead as long as his skeleton remains intact. However, that does not mean he is no longer susceptible to damage, and he has received a lot during his voyage with the Straw Hats. What comes as a surprise, however, is the fact that he can regenerate his cracked and broken bones simply by consuming milk, a phenomenon that is also exhibited by Luffy.
This ability wasn't granted to Brook by his Devil Fruit, given that the rubber man has also demonstrated it on various occasions. The reality of the matter is much simpler. It is a running gag, but a necessary one. It is a known fact that milk is rich with vitamins and minerals that are healthy for the bones, and Brook is nothing but bones. Thus, the gag. However, the importance of this joke resides in Brook's vitality. Since he is purely made up of bones, he no longer has any natural regenerative ability. Accumulating damages would warrant Brook's early retirement from the series, which is both an unlikely and unwanted scenario.
Walking on Water
In order to be resurrected by his Revive-Revive Fruit's powers, Brook's soul had to first find his corpse -- or what remained of it. This took a while, and when he did eventually return to his body, all that was left of it was bone. Because of this, Brook's weight had drastically decreased, allowing him to move faster and jump higher.
This quickness has given the skeleton an edge over his opponents, and it also granted him a movement skill. Being lightweight allowed the skeleton to run across water without sinking, just skimming the surface of the water, which arms him against a Devil Fruit user's weakness to the sea. The convenient ability prevents him from drowning to death -- not that he could since he's already dead.
Separating Body and Soul
During the period the Straw Hats were separated, Brook became a famous singer and earned his stage name: Soul King. He got in sync with his Devil Fruit powers during this time and discovered more of its abilities. He can manifest soul tendrils to reconnect any severed body part, allowing him to maintain his anatomy. He can also separate his core soul from his body.
After the separation, Brook's soul can roam around at will. He has passed through walls and floors while in this form, making it a perfect ability for spying and scouting. However, this skill has a few downfalls. Once his soul leaves his body, his skeleton returns to an empty and defenseless husk, leaving it vulnerable. His soul form is also only good for reconnaissance, since he can't touch or physically affect anything in that state.
Soul Music
Brook has been a devoted musician, even when he was still part of the Rumbar Pirates, and he has only increased mastery of his music skills since then. During the Straw Hat Pirates' two-year separation, Brook learned how to weaponize his music. He can play a piece and make his opponents believe they are in a different setting. Similarly, his playing can induce sleep if used in tandem with his Devil Fruit abilities. He can also use his music to boost morale during battles, as he had during the fight between cult members and the invading Longarm Tribe.
Brook has acquired numerous abilities during his two lives. A lot of those powers allow him to stand his ground, even when facing droves of enemies. However, many of his strangest skills aren't just used for fighting, which makes the lovable skeleton an all-around bone fide realistic and interesting character.