Arm Unit

Arm Unit (腕ユニット) is a defensive weapon introduced in the Rebuild of Evangelion film tetralogy, first appearing Evangelion: 3.0+1.0 Thrice Upon A Time. It is seen guarding NERV HQ, fighting against New Unit-02α and Unit-08γ.

Profile
Similarly to the Mark series of Evangelion, the Arm Unit is a specialized unit unlike the General-Purpose Evangelions units operated by WILLE. Based on the design, it is unclear how this unit is operated, however it appears to be quite effective given its lack of legs as they can be seen holding their own during their clash with New Unit-02α and Unit-08γ.

Features
Each unit possess two arms, two shoulder pylons (containing SHV Progressive Knifes) and is held together by a sphere at its center. While they are mainly seen fighting using their Progressive Knives, they also grab hold of their targets and use their ability to self detonate to create powerful explosions capable of damaging Evangelion, as seen during its conflict with Unit-08γ.

It is unknown if the units are autonomous or remotely controlled, however given the lack of entry point for a plug and no indicator of an external controller it is reasonable to assume these units are autonomous.

Evangelion: 3.0+1.0 Thrice Upon A Time
These units are first encountered by New Unit-02α and Unit-08γ at NERV HQ near the crater where Evangelion 13 is located. The units open with an attack directed at the New Unit-02α head, Unit-02 dodges the attack but isn't able to destroy them thanks to their confusingly high amount of agility. Eventually, Unit-08y is able to destroy one of the many units causing it to explode in a mixture of yellow and pink light. In order to escape the fight and reach Evangelion 13, New Unit-02α decouples its booster to explode multiple Arm Units giving it an opening to proceed further down into the Nerv HQ crater.

Meanwhile, Unit-08γ fights the Arm Units by using a beam whip to attack their the cores. One unit manages to get hold of the Unit-08γ left arm and self detonates leaving Unit-08 without a left arm and partially inoperable. The last three Arm Units grab onto Unit-08γ and explode, once again leaving Unit-08 without arms.

Ultimately, the purpose of the Arm Units was to force Asuka to become an Angel and initiate the next part of the rite to begin the Additional Impact.

Trivia

 * The name of this Unit was never specified on screen, leaving the name up to the Making Of video that was shared by khara.
 * It's interesting to note that Evangelion 3.0+1.0 introduced a NERV weapon with no arms in the form of the Evangelion Mark.44B and this unit, consisting almost entirely of arms.
 * The design is similar to the Dwarf Gekko from the Metal Gear franchise.