Indeed, they are a faction to be feared and to be overpowered and hated by all faction, while it of course hates all factions. Their weapons are highly destructive, with drawback being them needing a lot of Ordnance Points and they use a lot of flux. Of course their ship are made to be able to handle that and be overpowered like their weapons.
If anything they are a slow painful death. The larger ships of their are really show, although Paladin does has a dash attack (I really wanted to call it that). But I know after fighting them, that in battles with them I should not take anything but cruisers and capital ships, that of course are badass.
But this faction is made for one reason "To annihilate anything that gets close to them."
Amusingly enough in 0.65.2a in the handful of playthrough I had with Nexerelin, they were one of the first factions to get destroyed, thus I never met them until I played a modded 0.7.1a game... I was glad I did not meet them before XD