The Nocturne is the signature sword used by the Deckers. The Nocturne is not used by any other gangs and it has no upgrades. All Deckers carry this sword except for Decker Specialists, who use the Shock Hammer instead.
It can only be swung sideways with both hands, unless the person is lying down then the player will swing straight down.
The name 'Nocturne' is a possible reference to the song of the same name by Daft Punk, made for the movie Tron: Legacy, by which the Deckers' use-net was inspired.
This blade shares its name with one of the blades used by Nyte Blayde.[1] This may be due to Matt Miller, the leader of the Deckers, being a fan of the show, which he professes to in the mission "http://deckers.die".
Although all Deckers carry a Nocturne sword on their backs and use it as a melee weapon, it can't be acquired from them by any means. Even if disarmed with the Human Shield, they simply will not drop the sword.
The chain and charm on the handle are a reference to various anime and video game characters who have things like that on their weapons. For example, Squall from Final Fantasy VIII had chains and charms on his weapons.
In the Japanese version, the name of the Nocturne is "デッカーソード", which translates to "Decker Sword".