Sorry, I can't test it anymore. I got it built, on two fortresses and was trying to get a hold of an invader, wild animal, uninvited guest, or something similar to stand on the trap, since apparently that's the only way they will go off, I messed with all the mechanics and reread the entire wiki page on traps, and the only way for a weapon trap to work is when a hostile is standing on it, i think this in itself makes this whole thing a little less practical since it probably won't allow friendly fire even when it's being activated by an enemy, and the enemy also has to be on that specific trap, not any sort of trigger mechanism, for it to even go off. I never managed to get anything hostile in there. I'm currently stuck at my grandparents house with their computer, an ancient thing my dad gave them, no ability to run dwarf fortress, and I won't be back for several days. If you can run tests you probably should, multiple results are great. after realizing that weapon traps aren't just automatic, but cannot be linked(wired as i like to say, lots of gmod) to any other devices, I was suddenly filled with doubt as to whether it'll work at all the way it's intended. it does stack the odds in your favor having dozens of animals running through a hall of weapon traps, where the enemies chasing them are repeatedly hammered into paste, but that's probably about it.
Dropping a horde of stray(so there are no tantrum spirals from pet death) animals from the ceiling is a great way to delay/distract enemies in the first place (if they don't ALL flee towards your fort), hence the old puppy catapult idea. Filling them with war animals, especially tougher bears, is a great defense.