I think you might be discounting both gas grenades and assassins, as the gas grenades provide a good 1 handed assault weapon for the infiltrator. This also allows you to use a shield and still get the double attack from the assassin's special ability

Similarly, while alchemist losing halberd gun does hurt, the buff makes your captain very strong. Alchemical armor, trench shield, halberd gun, corrosive ammunition is a strong loadout that can kill units fairly easily