So, in Evangelion 3.33: You Can (Not) Redo, Shinji is forced to wear a Deep Synchronisation Suppression choker around his neck that, as the name implies, will explode if it detects synchronisation with an Evangelion unit.
Near the end of the film, Kaworu takes it off him and puts it around his own neck, which ends up killing him. This observation came from a friend of mine, but analysing the scene, you can see that the choker doesn’t do much when taken off Shinji.
So I ask: What’s the actual security on the device? Why couldn’t Kaworu, at an earlier point in the film, have taken it off and thrown it into the abyss?
I understood it as Kaworu’s love or friendship with Shinji. But the actual technicalities of the choker, I don’t think there’s a lot of explanation in the film (or I just don’t remember). Probably just a plot device or something. Shinji was wearing it at the end of the movie with Mari so it doesn’t make a lot of sense other than being purely symbolic.