[Lazy_Perfectionist]

First disclaimer: These are ideas- not anything backed by any sort of experience or heavy thought.

Water:

Evo 7: Ice Strike
Area attack, ignores cold resistance. And while the manual isn't perfect, it doesn't appear to be mundane or magic resisted either. Equip Skratti or Niefel Jarl with Robe of the Sea and Water Bracelet for larger effect.

Thau 3/4: Curse of the Desert, Sailors Death. Nah. These glamour horseman are mages as well, right, with MR of 18? Not much will be getting by them. On the other hand, Sailor's Death will be murder when it actually hits. You have to pay a rather hefty price to cast it at a necessary saturation, though, even with penetration boosters. Nah. Desperation move, perhaps. Not counting the chance of it hitting the right square, it has only a 6% base chance of success.

Quickened Water Elementals- Brings a lot of attacks to the table- six apiece, or -12 def on the last blow.

Astral:
Star Fires at evocation 1 is precise, armor negating, and not resistable. It'll take off a third of their hitpoints. Not even AOE 1, unfortunately.

Stellar Cascades: Only fatigue damage, but no mr check and its area-effect, precision 100. If you're going to win anyways, it'll speed up the battle by lowering their attack, defense, and increase their vulnerability to criticals. At worse, if it becomes a battle of attrition, it means you're still awake at the end.

Blood:
Blood Burst, available at blood 1. You'll need a Sabbath to cast, though. But in exchange you get to ignore armor, mr, and deal 11+ points of damage.


Death:
Frighten
Darkness: Sure, it affect both of you, but it'll probably hurt them more.

Nature: Rather than poison yourself, why not try Breath of the Dragon or Poison Cloud? Both are AOE.

Equipment:
Several Bows of War are likely to saturate even glamour, leaving you one less layer of defense to deal with.

Eye Shield- blindness does have a negative affect on defense.

Copper Plate: Charge Body (20 damage)+SR. One instant death to an attacker. Just clear out chaff first, so you don't waste it. And then, they easily couner with 5 fatigue Shock Resist. You might have better luck having your Niefel Jarls cast instead of equip, just once.

And give lightning a try. I don't know all the details, but that 'hit' tag is promising.