spoiler? Bug? Or just good technique?

I killed fargus with my survivor without using any potions, without taking any damage, and without allocating any skillpoints or even using any spellpoints. Well, perhaps using sneak cost me some spellpoints. I had a bow, and I discovered that if you open the door with sneak mode on and go only just inside the doorway and stand in exactly the right spot he will say his dialog but not move to attack you. There's a table sort of between you and him. You can hold down shift and hit him with arrows. It took me a couple game reloads but eventually I killed him using about 17 arrows (no better than half hitting) and him not moving or healing. This was playing the demo so I can't say if this works in the full game.