So Torpedo Spheres are good, then? I'm glad to hear it. I've yet to play as Eriadu, though I'd like to at some point, mainly to try out the Torpedo Spheres. They look like they could be cool, although I've been worried that they don't have enough firepower. I'd like to try making some fleets based around some of the more 'odd' units, like Torpedo Spheres for Eriadu, or World Devastators and Modular Taskforce Cruisers
(I can never remember what those things are called; I had to look them up on the wiki again to see) for the Remnant.
Maldrood's the one faction I've played for any serious length of time so far in 2.2, and I still have yet to really figure them out. (Also my save is now broken. Yay.) I agree with what you said about the Arquitens; I can't really see their role. I'm not sure if they're much good at anti-fighter duties, but neither do they seem much good against bigger ships. If they had the "boost weapons power" ability, that might be different, but they don't. I'm continuing to give Procursators a chance, partly because I think they look cool and partly because their "boost weapons power" ability lets them do a lot of damage quickly, which can come in handy if I need to focus an enemy capital ship down fast. They're not up to taking a lot of hits, though. Also, Secutors seem to be awesome carriers.
Also, something I only recently discovered about Maldrood: if you're playing ground battles, AT-APs
are awesome. Heavy damage with long range.