One-winged Kor

A One-winged Kor is a human that only has half a soul, thus only having one Kor wing.

One-winged Kor are created by Ayanami and are a result of him trying to control a person's soul using Vertrag's Ghost ability. However, due to his human body he is only able to imperfectly use Vertrag's power, resulting in a Kor with only one wing.

Ayanami has said that once a person has become a one-winged Kor their soul cannot be saved like that of a normal Kor. Instead they will be forced to reincarnate. The Kor wing eats the soul of the person.

Etymology
In the Ainu language of Japan, there is a closed class of 'count verbs'. The word 'Kor' means 'to have something'. 'Kor' is also an ancient Hebrew unit of capacity equal to 10 baths or 10 ephahs (source: The Free Dictionary).

Anatomy
A one-winged Kor still resembles the human it used to be; the only difference is the single, large Kor wing that is roughly six foot in length.

Temperament
Like the Kor, they are very aggressive.

Creation
Because Verloren devoured the soul of Vertrag, the Ghost that can possess souls, Ayanami has the ability to possess souls by making a contract, as seen in Mikage's case. However, while in a human body, Verloren can only use this power imperfectly, hence possessing only half of Mikage's soul. Even so, this is still enough to allow Ayanami to control a person's movements and what they say. It is currently unknown for how long he can possess a person's soul and if this works on anyone. It is also unknown whether he can use his full power when possessing someone but it is likely that he is limited to an extent, although not significantly.

In the manga, it has been said that a soldier became a one-winged Kor because he was not baptised, which suggests that those who are baptised receive protection against becoming one.

Why the Kor has only one wing is never directly addressed in canon. One theory is that it's because Ayanami only holds half of the person's soul, and therefor the resulting Kor has only one wing. It's also noteworthy that the single wing is always the left wing, which in his true form, is the only wing Verloren possesses; his scythe transforms to create his right wing.

Attacking and destroying a one-winged Kor
Unlike with a Kor, destroying the wing will not release the person's soul. It will instead kill them. It appears that destroying the wing is the only way to destroy the one-winged Kor.

Abilities and Attributes
When possessed, the person's speed and strength is enhanced greatly due to Ayanami's own immense speed and strength. Their movements are difficult to predict. Ayanami, while possessing Mikage, has also demonstrated the ability to fly and become intangible like a ghost.

A possessed person also has a greater resistance to injuries that would seriously harm or kill a human.