New version (RC1.0.3.0) has been uploaded. This should fix the problem where the players weapon does not swap to being the Blood Dagger. The point of collecting this weapon is to defeat the final boss, but the bug meant that it was not even used in that battle. This should now be working, and it should allow your save game to be loaded and immediately reflect that this weapon is now in hand.
The Blood Dagger is a very powerful weapon and as such it should be an instant kill to all minions, but only Mordeth is able to withstand the damage.