[Edi]

Definitely slap more HP on the angels, equal to the devil's maybe? 100 FR would also be fitting. They already have FR 50, and the Flambeau should give them another 50%, but because it's intrinsic instead of an item, it does not, and the archangel will fry his minions half the time with falling fires, fireballs and other offensive fore spells.

Blood summons are available far earlier and are much cheaper and use a type of magical resource generally not suited to much more than summoning nasties, while the angels are expensive, die quickly and the resources generally are much better used elsewhere. It is quite telling that you generally need to drop at least two Angelic Hosts on a moderately large indie province (at indie strength 7) to conquer it with them, and even then you will lose two to three of them, most likely because the Archangel will flashfry his minions with fire magic instead of laying the smackdown on the enemy.

Tight now, the angels are a completely losing proposition almost every time, unless you have insane amounts of astral pearls to spare or find a conjuration bonus site like The Crypt Underneath or The Ultimate Gateway. With the latter one, they become a viable option, but that site is very rare.

Edi