I beat them by kiting/breaking them into smaller groups with cavalry, I didn't even participate in the fight until the end. I had about 50 archers(vaegir troops), 50 heavy infantry(swadian shock troops mostly) and about 20-30 cavalry.
Hide behind a rock. Open up the battle map, tell you archers to move to one flank, your infantry to the other, but slightly closer so if the fallen ones get close, they will target the infantry and not the archers. Tell your calvary to go to the opposite side of the map, luring the majority of the fallen away. The other fallen will continue to go after you infantry/archers. They will take heavy ranged fire while approaching your units, if the get too close while their is still too many alive, tell your infantry to move back, then when they have few left, charge, kill them. all the while kiting the main force with your calvary. Move your calvary back to your infantry. wait until the fallen ones are half way, then break them up again by luring them away with the cavalry... repeat , your archers will go out of ammo fast though. Resort to overwhelming numbers in the end. The perished one is a real bugger to kill.
My battle size is 120 I think. The higher you can get it(and your army). The easier it should be to destroy them.
But yea, that's how I did it. Unfortunately I did not get a death ward that time(and died not long after...). I had no companions either and we killed them in one battle. Not guaranteed to drop? Perhaps I missed it in the loot. I don't know.