About earlier posts in beginning of topic I think you don't know what Terran&Vasudan capital ships are for.
Fenris/Aten - total piece of junk, used only as anti-fighter cover and discraction.
Leviathan/Mentu - medium AF protection (four AAA cannons on Leviathan and three AAA+three flaks can hurt fighters, also Mentu has got pretty strong armor because of its large size and young age).
Aeolus - ultimate AF protection, but very expensive because of its two SGreens and replaced by Mentu cruisers.
Deimos - escort&patrol corvette, very good against fighters, support in destroyer extermination.
Sobek - assault version of Deimos, has got the same firepower as Terran counterpart, however it's concentrated entirely on top making it better in attack missions (and Sobek would own Deimos, you've had driffent results because you've probably FREDded those missions wrong, really Sobek should stay 4000m from Deimos and DON'T MOVE while Deimos should try to close to it, when Deimos closes to Sobek, it's got around 20% hull left while Sobek 60%, in manevuer fight Sobek should survive with 20%).
Iceni - assault warship of future, 300m longer than Deimos, but having AC firepower of Hatshepsut (note its AF weaponary isn't too strong). Its power is because of young age and lack of fighterbay. Iceni might've conviced GTVA command to specialised warships (just imagine two Icenis attacking Ravana, that'd be firepower of Colossus)
Hecate&Typhon - stays back from fighting sending fighters and moves into combat only when nessesery (also as I said before in another topic Command made one fatal error in desinging Hecate - it could have 300 fighters if it had no Anti-Cap weaponary making it real carrier, Hecate's beams decreased fighter capability seriously).
Orion - old destroyer modified into powerful Capship-Killer. Almost always with cruiser escort/fighter protection.
Hatshepsut - next generation of AC destroyers. Better armor and AF protection.
And Slash-type beams are very good. Altough they deal less damage than standard beams, they've got one large pros - they're very good in disarming warships. Basic rule is that Slash-type beams are for carriers (like Hecate) while standard beams for Capship Killers.