feel irritated every time this topic comes up and pilots trot out the 'we are above reproach because we are pilots' speel. You are humans, though some might have trouble remembering that, and that means that there will inevitably be bad 'uns of varying degrees amongst you. Pilots have had pressures so severe that they have hanged themselves down route, been caught smuggling, etc etc. So whilst 'you' mght be lillywhite and clean living please don't think that all pilots are like you.
You might like to cite me just
ONE instance of where an operating crew member has hijacked/attempted to his own aircraft.
The point is, operating (pilots) crew DO NOT NEED any weapon, they already control the aircraft!