I didn't have any problem killing them with my warrior / archer combination in tactical, and did not attack in sneak mode. I brought my warrior up first, so he would be the target of the DK patrol, with my archer following behind to start attacking immediately when one appeared.
I used the same tactics, only with the DK as warrior and my char as a mage/archer. Worked great, as long as I got a little lucky and remembered to pause and use healing and mana potions in a timely fashion.
