Soul Solid

The Soul Solid is the name of Brook's cane sword. Since he only gave the name of the sword after the timeskip, it is unknown if his sword always carried this name.

Appearance
It looks like a regular cane, with the hilt of the sword also serving as the handle of the cane.

Abilities
Not much is known about the quality of this sword itself, though presumably it is of a higher quality than his old one. Brook is able to enhance its power by enveloping the blade with his soul using his Devil Fruit ability. The energy of his soul brings the "very cold of the underworld into this world," resulting in the sword being freezing cold. He would utilize this enhanced blade with his swordsmanship.