Anybody know how to disable weapons in Certain difficulties?

[Chopper]

I've been modding Doom 3 for a while now and I've learned some pretty neat tricks that each of the maps do, a bunch of items are removed from each subsequent difficulty with the commands "not_hard" or "not_easy" for example. However, there is no such command for nightmare, since it shares it with Veteran difficulty, so I can't really fulfill my wishes in making a Tyson-style difficulty. I already tried to look through the .def and .script files but to no avail, so I'd like to know if there's a certain command in a certain file that would allow me to remove weapons from the nightmare difficulty. As far as I know there isn't a .def or .script file for difficulty but I could probably put in a sys.getcvar() in a script file to remove the weapons.