So... it seems logical to me that it should be possible to make a trap that is just a device for automatically dispensing a Grenade, if you know how to make (or acquire) both. Contemplating rules for doing so.
Maybe an Additional Effect of a trap could be Dispense Grenade, Journeyman and Master Only, -4D6 damage.
What do you think?
I was also considering whether Grenades and Traps should be able to dispense Poisons. But the implication of poisons seems to be that they need to be ingested or injected (via stabbing), so using a grenade probably isn't logical. And they need to be administered shortly after being applied to a weapon probably wouldn't work for spike or dart traps.