Some ideas:
Arceans:
-Super tractor beams that pull you to their ships on contact, acting like feline claws on their prey.
-Short range missiles, not like rams, but with high penetration levels.
-A single boost shot, something like nitrous oxide on cars, which allows them to jump on the prey.
Drengin:
-A cannon with high explosive capabilities for orbital bombing
-Torpedo bursts, somewhat like rapid2, but with short duration, shooting about 12 torpedoes at the speed of a rapid2, with reloading capabilities.
-Temporary shield improvements, which allows them to reload weapons while taking fire. Give them like 3 of these, reloadable when docked.
Terrans:
-Kind of a flak gun on heavier, slower ships, which doesn't actually hit the ship but causes some splash damage, lethat on smaller ships.
-An explosive grid, for skirmrishes with large numbers of ships.
-An EMP missile which disables shields and prevents them from reloading for 10 seconds (to say something).
