There are now only two engineering trades in the FAA, Mechanical and Avionics (M and Av). You'll find that the RAF and Army, if not already, will soon be the same in this new 'purple' world.
Arming is usually carried out by Av's, trying to get an 'M' (grubber) anywhere near anything that gives fizz or bang is nigh on impossible.
Apart from engineers, you have Aircraft Handlers (Chockheads), Phot Ratings, Survival Equipment Ratings, Air Traffic Controllers, Fighter Controllers and Met Ratings. I apologise if I've missed any but my head is hurting.