Foudre is a set of Knives that can be wielded by Larxene in Kingdom Hearts 358/2 Days. In Kingdom Hearts II Final Mix, Kingdom Hearts Chain of Memories, Kingdom Hearts Re:Chain of Memories, and Kingdom Hearts III, the Foudre is her only weapon.
A Knife from the Foudre has a cross shape and is designed to look like the top half of the Nobody logo. One of the spikes is elongated and acts as the blade of the knife, while the other three act as the grip. The base of the blade is cyan had a clear separation from the blade itself, which is bright yellow. The other three spikes are a slightly paler shade of yellow and each has a cyan tip (again, a bit paler than the cyan in the blade). These two colors fade into each other, unlike the clear color separation present in the blade.
Both Foudre and Éclair are French for "lightning", fitting for Larxene's element. Although having a French name, the Foudre is named Blitz (also meaning "lightning" in German) in the French translation included in the North American game, similarly matching Larxene's element.
On the ground, Larxene will rapidly hit enemies with diagonal slashes from the left hand and end with a large spin. While in the air, Larxene will hit the enemy once with an upward diagonal slash, followed by a downward swipe with both hands, and ends the combo by striking the enemy as she somersaults in mid-air and does a powerful downward slash. If one presses when during the first or second hit on either combo, she will jump into the air and do an aerial backflip while throwing her Knives into the ground.