On master, I was in an even worse situation. A Lvl 14 archer in light armor against a group of four scourges and one deathlord it's totally unfair. I won't lie, it took me more than a half an hour to beat them. I'd say it's a buggy random spawn. Here is the proof: this guy fights at lvl 38 on the same difficulty against regular draugrs, at worst restless.