The Ultimate All-Purpose Humanoid Decisive Battle Weapon: Aesir.
The Aesir are, put simply, forty meter tall biomechanical robots. They were created by the NERV organization for the purpose of defending humanity from the threat proposed by the Jotun, who appeared some time after humans had adapted to live in the Fimbulvetr.
They utilize the same type of energy that the Jotun use, what the scientific community has dubbed the Absolute Territory Field. Though only a fraction of the ability present in the Jotun can be utilized, it is enough that with a capable pilot, the Aesir can produce a field strong enough to neutralize that of the Jotun and allow them a fighting chance against the otherwise impenetrable foes.
The only way to utilize the system, however, is through synchronization with the organic parts of the unit. The necessary brainwave to allow this synchronization to take place has, thus far, only been known to develop in children born after 2015. Synchronization with a Unit allows the pilot to control the Aesir and its AT Field as an extension of his or her own body and mind, respectively, which allows for optimal control and the only manner in which the field can be used to neutralize others, and theoretically be used for many other application.
The apparatus used to synchronize is known as an entry plug, a long cylindrical object inserted into the back of the Aesir’s neck, into the spine. It is then filled with a translucent orange fluid known as LCL, which boosts conductivity for synchronization between the mind of the pilot and that of the Aesir. Once active, the monitors and displays in the entry plug will light up with what the Aesir “sees” on the outside. The entry plug also houses a number of technical equipment, controls for more precise operation, and medical kits for emergency use.