The GAT-04 Windam is developed from the GAT-02L2 Dagger L and is the most advanced Earth Alliance mass production mobile suit. It is more mobile than its predecessor due to the additional vernier thrusters mounted on its legs and shoulders, and has higher performance that is comparable to the ZAFT's ZAKU-type mobile suits. The newly designed feet allows the suit to walk more easily on uneven or difficult terrain. When piloted by a skilled pilot, the Windam can prove to be a challenge even to Kira Yamato's ZGMF-X10A Freedom.
Weapons wise, the Windam's standard armament is similar to the Dagger L and includes CIWS guns, beam sabers, anti-armor penetrators, a new beam rifle and shield. Like its predecessors, the Windam has the ability to mount Striker Packs, however the design of its shoulder armor prevents it from mounting the Sword or Launcher Striker Packs. The Windam has been seen mounting the Jet Striker, Doppelhorn Striker, Aile Striker, and the new Multi Striker Packs.
The Windam is equipped with four CIWS guns to shoot down incoming missiles or enemies at close range. Two are located in the head, while another two are located on the clavicle.
ES04B Beam Saber
The ES04B beam saber serves as the Windam's standard melee weapon, and its beam blade is capable of cutting through most non beam-resistant material. The Windam is equipped with two beam sabers stored on the top of the side armor.
Identical to the ones used by Dagger L, these penetrators are dagger-like weapons, which are stored inside the suit's side armor. They can be used for close combat but are most times used as throwing weapons, which can destroy a mobile suit if they hit a critical spot.
A52 Offensive Shield Type E
Mounted on the left forearm and/or handheld, it is a physical shield used to defend against enemy attacks. The A52 Offensive Shield Type E is a new type of shield and is named as such as it carries missiles.
Mk438/B Dual Multipurpose Missile "Würger" SA10
The shield mounts a Mk438/B dual multipurpose missile "Würger" SA10, giving it some offensive power.
M9409L Beam Rifle
For ranged combat, the Windam is equipped with a M9409L beam rifle. This new beam rifle is larger and more powerful than the beam carbine used by the GAT-02L2 Dagger L series.
As with the old GAT-01A1 Dagger and GAT-02L2 Dagger L series, the Windam is capable of mounting Striker Packs, thus being able to adapt to different missions and environments. Among these are the AQM/E-A4E1 Jet Striker, which gives the Windam atmospheric flight capability, the AQM/E-M11 Doppelhorn Striker, which is for artillery bombardment, the Multi Striker Pack, and the old AQM/E-X01 Aile Striker, which can be used as an alternative to the newer Jet Striker. The Windam however has considerably different shoulders than the previous GAT-01 and GAT-02 models, and is probably not compatible with Striker Packs that use shoulder-mounted weaponry, like the AQM/E-X02 Sword Striker and AQM/E-X03 Launcher Striker. Although it could be mounted with the Another Trial versions of the Sword and Launcher Striker Packs developed for the Strike E.
The Windam was introduced in October CE 73, when a squad equipped with Multi Striker Packs was sent to destroy the PLANTs, shortly after declaration of the Second Alliance-PLANT War. However, they and their supporting fleet were all destroyed by ZAFT's Neutron Stampeder. Soon afterwards, Windams equipped with the Jet Striker were deployed to oppose ZAFT's "Operation Spear of Twilight", in which large numbers of mobile suits were dropped to Earth to reinforce their Carpentaria and Gibraltar bases. Windams were also employed in a failed attempt to destroy ZAFT's battleship Minerva as it left Orb territorial waters, and in most major Earth Alliance operations on the planet thereafter.
Neo Roanoke, commander of the 81st Independent Mobile Battalion, piloted a custom Windam with a unique purple and dark gray color scheme, operating from the aircraft carrier John Paul Jones and later the land aircraft carrier Bonaparte. Windams were also used by the renegade Earth Alliance forces that sided with ZAFT after the existence of Logos was exposed, and they were deployed during the battles of Heaven's Base and Orb. The Windam was also used in large numbers in space in the last month of the second war, during which they were deployed without any Striker Pack or with the Doppelhorn Striker. The Windams were used to protect the emitter of the Requiem superweapon at the Daedalus lunar base as well as its relay stations. At the end of the war, a dozen Windam joined Terminal to destroy Requiem.
While some materials such as Gundam SEED DESTINY MS Encyclopedia state that the Windam has VPS armor and while wrecks of PS-down Windams can be spotted, it's contradicted by the fact that Windam can be damaged by all sorts of projectiles, explosions, missiles and even the LHM-BB01 Minerva's 40mm CIWS. Other sources such as Gundam Fact Files list its armor as unknown.
In Mobile Suit Gundam SEED Battle Destiny, the Jet Windam can only be used in the atmosphere, while the standalone Windam and the one equipped with the Multi Striker Pack are exclusive for space-use.