Shiki ate the Fuwa Fuwa no Mi, a Paramecia type Devil Fruit which allows him to make surrounding non-living matter levitate once he has come in contact with it.
He seems to have mastered the use of this fruit, as he has shown a variety of skills which manipulates the surrounding non-living environment in complicated ways, even manipulating it from its simplest components, such as earth’s fragments and snow flakes being used to build up gigantic, elaborate structures that are then used to attack for a variety of purposes.When attacking, Shiki uses the surrounding environment against his enemies, shaping earth or snow into giant lion heads and launching them towards his foes, or even making water float to drown his opponents in it. As stated, his powers are unable to be used on any living matter other than himself, meaning he cannot touch another person, animal, or plant and make them levitate.
He also possesses great skills as a swordsman and was able to kill a mountain of Marines before getting captured.
After the two swords became his new legs, Shiki is also capable of attacking from a distance with them, by sending slashes from his sword legs in a Rankyaku like fashion. These air-blades have a light-yellow/gold color-scheme, matching his epithet.
He also combines his sword skills with his Fuwa Fuwa no Mi, such as slashing open a body of water and then levitating it to drown his opponents. He fended off all the slashes from Zoro’s Nanajuni Pound Ho with great speed and reflexes, and later another attack from Zoro’s was countered in mid-air and he knocked Zoro back down to the ground with great force. He was also able to fight on par against Roger, and later, it took both Garp and Sengoku in their prime to capture him alive.