I'm assuming we're going to ignore timeliens in favour of having eventually every empire available in game. So I have a few idea's for the Drakh.

Shadow's always used their middle men first before coming out of their closet so to speak so my suggestion would be have the Drakh be the first tier of vessels in each category (fighter/corv/cap etc) for the Shadow faction. They're strong, but no way near Shadow strong, so having them as the first tier of Shadow vessels for the shadow faction makes an odd sort of sense.