Something else I see our Acillians and Skitarii doing is the use of their extra arms to easily manipulate and stabilize heavy weapons that normally require two arms.
General Castor for example, has a special bionic arm that lets him easily manipulate his sniper rifle with pinpoint accuracy from one hand, connecting its optic to his mind.
Perhaps our Mortal Auxilia can dispense with lasguns and use hellguns exclusively. At least until we can get them something even better.
https://youtu.be/SfRMbq4-c3gThat's not even including the shoulder mounted weapons with or without automated servo-skull targeting.
