What were you expecting, a +5 Holy Avenger? Fun to try and if you succeed, brag about, but they weren't meant to be beaten. Maybe there will be a steam achievement once it goes live. Loot though, not so much. Grats on killing them, haven't been able to yet.
I think some kind of cut scene, dialoge or some bonus gear would be pretty - at least the fact that the mindflayer stays dead and doesnt turn people later.
They already did something similar in DOS 2 when you beat Dallis in Fort Joy and rewards you with a good starting weapon - and Demon Souls also rewards you with something cool but nothing OP as well if you beat the Tutorial Boss.
