I recently got the dragon slayer edge and am having trouble seeing the increase in damage so far. I only had a fight with the dracolich logged before I got the edge, but from the log, It doesn't appear that I'm doing additional damage.
As an otyugh, On unprotected foes, I do EVISCERATES to MASSACRES On dracolich (pre and post DS) I do devastates to maims. On green dragon (post DS) I do maims to MUTILATES. On red dragon (post DS) I do maims to MUTILATES.
Again, on the last two, I don't have logs of pre-DS edge.