Phantoms

Phantoms (ファントム Fantomu), formerly Spirit Knights (精神騎士 Seishin Kishi), are entities imbued with life with the powers of the Haki Haki no Mi. As physical incarnations of Demas' spirit, they are affiliated with the Phantom Pirates.

Appearance
Phantoms are blue spirits clad in a dark armor, said to have been forged with a legendary metal, and wield the massive Phantom Sword. The armor in particular has a strange design on the chest and back, also seen on Demas and the Ghost Ship.

Abilities and Powers
Phantoms are notorious for their near-impenetrable armor and powerful swords, which combined with the incredible strength inherited from Demas, has earned them a reputation for being "invincible." In fact, the World Empire has issued them bounties of 100,000,000 each.

Weapons
The Phantom Sword (夢幻の剣 Mugen no Ken) is a powerful sword wielded by Phantoms. It is a massive broadsword, at least three times heavier than regular ones, that can only be handled by Phantoms and Demas himself. It is said to have been forged with a legendary metal.

Trivia

 * The Phantoms are based on the enemies in The Legend of Zelda: Phantom Hourglass.