Quote: "Well, I guess it's good to hear now rather than later. Maybe I can still get around it with the swapweapon command in Fenix Mod."
Yep but you're going to have ammo problems if you use swap weapon functions because Fenix doesn't have ammo pooling (last I checked) and it doesn't have a way to store the ammo count of the weapon in the gun and apply that to the swapped weapon. So, every time you "turn on the light" via weapon swap, it would reset the ammo count.
PB is supposed to store the ammoingun as an internal var, but that is currently broken, so no help their either. There's still a long ways to go before we'll see any sort of robust weapon scripting ability with FPSC. The weapon scripting in PB is currently about all there is but you only get 5% or less of the normal FPI options which are compatible with HUD weapons(maybe 10% if you include globalvar reading workarounds).
It would be a pretty sweet feature to be able to "hide" or "un-hide" a named limb via weaponscript. Then, you could easily toggle a light-cone on/off (or toggle any number of component accessories, really).
...However, even if you could toggle a light-cone mesh on/off there aren't any shaders which correctly support illumination maps, at present. So, if you went into shadow, your light cone effect wouldn't glow and would just look pretty stupid.
We've come along way with things that can be done with HUD weaps but there's still much room for improvement. This will likely never be a priority for TGC so it will likely fall into the hands of modders.
For now, the best alternative, IMO, is to script the light to check for whichever specific weapon and automatically activate it when the weapon is being held and turn it off when it is not being held.