The Weapons Depot is located within the Gear Factory and is a repository of the nanoweapons you have already created.
Here you Enhance, Promote, Share, or Dismantle any weapon.
Here in this example you can see a Common Terrestrial Radar, its Troop and Hero Stats. (Note because the Terrestrial Radar is a generic hero weapon, it gives no Exclusive stats, which would be listed below the Hero Stats.)
Enhancement and Promotion of Weapons
When you click on Enhance you can see that much like other things in game that can be enhanced, weapons are no different and take both Weapon Enhance Material and other weapons in the Depot as material that can be used to enhance it. By pressing Auto Select the game will select the most efficient way to enhance the weapon, (however it may not always select the desired materials, and you should always check before pressing Confirm.)
The same is true of Promotion. In this example the 4 star Terrestrial Radar can be promoted to a 5 star, however it requires promotion material that can be obtained while playing the game or by purchasing it directly from the Mall.
Dismantling of Weapons
Since materials are an important part in the production of weapons, dismantling unnecessary or redundant weapons allows the user to recover some of those materials, which can then be used in the production of new weapons.
(It should be noted that this is not the most efficient way to get materials for production, and should only be used when the weapons you are dismantling are redundant.)