This is a very specific timing issue with the Fezzerk interaction. As a Paladin with Wyll in the party, after Fezzerk surrenders, you have the option to kill him or let him go. As a Paladin, I opted to let him go instead of killing him. HOWEVER, the final blow against him was a crit, and so after the conversation had ended and I said he could go, I then (using the reaction system) said I wanted to burn a smite on that crit, which killed Fezzerk. I had the conversation with Wyll about letting him go, but was still able to loot him for his greataxe. I think this is specifically an issue of when the conversation trigger goes off, vs when the reaction engine goes off.
