i think i get where you're coming from with that

i do wanna state the item texture does have an alpha channel; it's a full sheet one that's barely noticable, but it covers the entire texture which is what i think causes the fullbright effect
in my experience, textures with $selfillum and no alpha channel don't glow at all [using half-life 2: survivor's gordon freeman sheet as an example] but i very easily could be wrong about this

regardless, i'll change the name and description to give a better impression

Technically no, the grenade with the light was seen in E3 2004 footage and was cut last minute but still present in the Xbox version apparently, i think its likely a mistake or a very specific optimization for its lack of inclusion.

The restored texture is from the leaked repo, and the vmt was pointing to the item version of the texture that lacks a alpha channel which is why its fullbright normally instead of the worldmodel texture with a proper texture and alpha.