Ace is a normal-sized cutlass with a slightly curved blade, with a saw hamon pattern adorned on the sides of the blade. It possesses a yellow hilt with diamond shape pattern, a golden guard, as well as a thinner hand guard running atop the hilt and a black sheath.
As one of the 12 Supreme Grade Meito, the quality of Ace's blade is ranked among the best, being one of the most powerful weapons ever created, rivaled only by a select few other weapons such as Whitebeard's Murakumogiri. It was used by the Pirate King Roger during most if not all of his great exploits, from the God Valley Incident to his battles with Whitebeard, and was never shown taking any damage, which served as proof of its immense durability. Roger frequently imbued the sword with Busoshoku as well as Haoshoku Haki.
- Kamusari (
神避Kamusari?, literally meaning "Godly Avoidance"): Holding his sword in his right hand, Roger imbues it with Haoshoku Haki and then swings his sword horizontally, creating a powerful Haki imbued slash attack to strike his opponent. It was first seen used against Kozuki Oden, hitting him in the torso with a burst of dark lightning-like energy, and was powerful enough to overwhelm the samurai's two-sword defense, sending him backward a great distance. In the VIZ manga and Funimation subs, this is called Divine Departure.
Roger was first shown wielding Ace 38 years ago during the God Valley Incident, using it during combat against the Rocks Pirates. Eleven years later, he wielded Ace alongside a flintlock pistol during the Battle of Edd War. A year later, Roger used Ace in combat against his top rival, Whitebeard, in their final battle which lasted for four days. Roger would turn himself in to the Marines to be executed two years following this, and it is unknown what became of Ace.
- Between his voyage and death, Roger would sire a son named Ace with Portgas D. Rouge, with Roger having specifically chosen Ace as the name were the child to be a boy. It is not known whether the name of this sword played a part in Roger's naming decision for his son.
- One Piece Manga and Anime — Vol. 0 Chapter 0 and Episode 0, Ace is first seen during the Battle of Edd War.
- Vivre Card - One Piece Visual Dictionary (Card #0014), The name of Roger's sword is revealed.
- One Piece Manga and Anime — Vol. 96 Chapter 966 and Episode 966.
- One Piece Manga and Anime — Vol. 95 Chapter 957 (p. 9) and Episode 958.