I would use the word engineer.
simply just the guy that invents or improves a weapon
mechanical or electrical engineering
I guess I was a weapon engineer once, but we never used that term. Aerospace companies prefer degrees in engineering, math and physics. There are so many facets to weapons (RF, digital, analog, mechanical, nuclear, explosives, delivery, repair, repairing the repair stations, etc.) that you can be hired for many different disciplines.
· Acoustic Engineer · Aeronautical Engineer · Aerospace Engineer · Agricultural Engineer · Airline Flight Engineer · Application Engineer · Aquatic Engineer · Automotive Engineer · Aviation Engineer
Handy Helper Engineer, Half an Engineer, Helping Engineer, Heavy Engineer, Hacking Engineer, Hey Engineer.
· Acoustic Engineer · Aeronautical Engineer · Aerospace Engineer · Agricultural Engineer · Airline Flight Engineer · Application Engineer · Aquatic Engineer · Automotive Engineer · Aviation Engineer
· Acoustic Engineer · Aeronautical Engineer · Aerospace Engineer · Agricultural Engineer · Airline Flight Engineer · Application Engineer · Aquatic Engineer · Automotive Engineer · Aviation Engineer
· Acoustic Engineer · Aeronautical Engineer · Aerospace Engineer · Agricultural Engineer · Airline Flight Engineer · Application Engineer · Aquatic Engineer · Automotive Engineer · Aviation Engineer
· Dairy Engineer · Design Engineer · Drafting Engineer
· Dairy Engineer · Design Engineer · Drafting Engineer
· Acoustic Engineer · Aeronautical Engineer · Aerospace Engineer · Agricultural Engineer · Airline Flight Engineer · Application Engineer · Aquatic Engineer · Automotive Engineer · Aviation Engineer