The Nocturne Blades are dark handheld energy blades crafted by the Nocturnus Clan an items featured in Sonic Chronicles: The Dark Brotherhood.
They are used for melee combat and can leech off opponents' life energy to replenish the user's own health. They are amongst the standard equipment for many of the soldiers of Nocturne, such as the Nocturne Decurions.
A Nocturne Blade can be bought by the player for 150 Rings during the second half of Sonic Chronicles: The Dark Brotherhood. It can equipped on any of the playable characters in the game to boost their Attack stat by 4 points.