[Endoperez]

Shadow Vestals are ethereal, which already makes them rather good at staying alive. Their spears are magical and deal decent damage. However, as almost always, Fire or Water bless will work better for just pure damage, and pure damage is very good when the units can already survive without the help of a bless. Minor Death bless is interesting, but doesn't win games. It can be used to bring thugs down, though. Death 9 isn't good for magical weapons. It's a bit better for mundanes, because it gives a small chance of magic damage (to get past ethereal), and a good chance to get past armor (AN, and most massable armored troops have lower mag res than most ethereal troops). Fire 9 Death 4-6 would be a nice offensive, "evil" bless. Of course, you should start that with a Fire pretender, to avoid negative scales.
Ermor gets away with Dead quite nicely. Death magic protects mages from old age afflictions, so Death scale doesn't hurt you as badly as other nations.

Most good Astral damage spells are in Thaumaturgy. Mind Burn is nice. Soul Slay is awesome, and Enslavement is nasty. Alteration has Body Ethereal, which isn't quite as good for MA Ermor as it already has ethereal units, but it is nice to make some ethereal Principes or something. Also, any S1 mage can cast Body Ethereal and Luck on nearby units, like your pretender... That's nasty on a Wyrm or something.
Death gets good summons from Conjuration, mass summons from Enchantment (including Raise Dead, which can be used to swamp battlefields with endless undead) and Drain Life (but not much else) from Alteration. Shadow Blast is very good Evocation spell, but it costs gems.
Astral/Death doesn't have many combinations, but they are rather powerful. Conjuration has Nether Gate, which is hideously expensive and summons a group of ethereal giants all armoured and wielding magic-slaying Moon Blades. Evocation has Nether Darts. Every caster gets at least 15 darts... And as Ermor, you have dozens of casters.