[Cohen]

Personally I find Caelum troops good.

Archers with precision 12 + wind guide.
All troops with defaul magic weapon.
Armors that get increased protection in cold provinces.
Flying army (they can swarm early rush pretenders before they buff, and they strike first).
They've Mammooths. Stompa Stompa of indies. (but they usually have better ways to conquer indies).

I'm playing Caelum in a game, and I'm facing Ermor by myself all alone. AE Ermor, so not so easy to cut down with lightnings and false horror (they don't rout, they're so many to lightning them all) and I cannot wind ride their better commander (ouch they're ethereal), but dunno why I've stripped them of every non castled province except one where there're a concentration of dusk elders (well however a Wrathful Skies raid had killed some of them and of the minor D2 leaders) ...
Yes now I've to siege ... uh oh ... wall shakers coming in, with some Harbingers thx to the massive clam I can forge with Caelum. CrushaCrusha. Not to say cold+sloth points = uber GK, + ring of wiz, +ring of sorc, +some death item = Death10 Undead Mastery (with +2 Penetration due to rings!).
Well this was is depriving me of many resources, so probably if someone attacks me later could have upper hand ... but it's easy and common for a third party to get over someone that has just finished an exausting war.

However, even if they've a not so good army, what matter, armyes become useless after turn 20-30 more or less.

Abysya has many more other weaknesses (costy troops/mages for what you obtain, problems in researching and blood hunting at the same time, are 2 of the most clear examples), not only the missing of fire troops.