I think weapons need some mass, at the moment you just buy your weapon an equip it and off you go.

It would be great if ships had more cargo space, for example take the Wraith. If the Wraith had 12 cargo slots you could fly it unarmed on trade runs using the max 12 cargo load. If you arm it putting in two light weapons an 1 heavy the cargo space would drop to the original 8 cargo capacity.

It would be a nice incentive for traders to fly unarmed for maximum profit an they could maybe hire wingmen to cover them.