then it's just abstract existence type 1 still. existing as a concept, being able to create avatars, and being unable to be affected is all under AE type 1. There isn't any mention of him lacking a concept of death, or something similar. and even though he does exist on a different plane of existence, it seems more like a sort of shadow realm, like yugioh's. and in general, characters with AE type 1 are just hard to kill without concept manipulation or existence erasure. And even then, you need NPI to even be able to touch them.
because of the NPI mixed with holy manipulation. because they have both, they are likely the only one able to kill him. like a type advantage in pokemon. where water is effective against fire, fire to grass, grass to water, and so on. so they can harm him, interact with him, and likely kill him.