Can anyone identify this item?

Looks most likely to be a signal flare pen gun launcher.

rc

Since they don't appear to be reusable like a pen flare launcher I'm guessing they're some variant of a Pencil Detonator, which is a delay switch used to ignite blasting caps - https://en.wikipedia.org/wiki/Pencil_detonator.

The front screws off so you can reload it.

rc

¿signal or alarm device?

Looks to me like an igniter for some sort of alarm or boobytrap. And someone pulled the ring on one to see what would happen? No thanks! I know what would happen if I did that to my old Penguin pengun signal flare launcher!! Not good, especially indoors!!! Cue: Deep Purple "Smoke on the Water"

Pen Flare igniter...

While I know it isn't, it looks like a tactical pen that can double as a kubaton.

If someone made a tactical pen that looks like that image, it would be badass looking IMO.