malcolm_n
Adventurer
Half-joking: A simple fix would be to give nobody proficiency with those weapons. You can buy it if you want, but that's a feat you're giving up. Classes still get proficiency with firearms by default since if you're a hero, you know how to wield them (whether or not you like to).
A more serious consideration would be to decrease the overall damage of melee weapons by one step since modern armor is more durable. Energy swords wouldn't suffer such a penalty, and you could build it into the soldier class (which is the most melee-centric of the classes) that he deals bigger damage if he so chooses. Failing that, I fall back to feats and crit buffs as already noted above; but I'll continue thinking on the matter and see if I can come up with better ideas.
A more serious consideration would be to decrease the overall damage of melee weapons by one step since modern armor is more durable. Energy swords wouldn't suffer such a penalty, and you could build it into the soldier class (which is the most melee-centric of the classes) that he deals bigger damage if he so chooses. Failing that, I fall back to feats and crit buffs as already noted above; but I'll continue thinking on the matter and see if I can come up with better ideas.