Fictional Skill

Just thought I'd mention that I literally encountered this exact bug today. I reloaded a save (at a point after killing Danna the first time but before returning to Mestre Verzano) multiple times selecting different dialogue options in the conversation with Mestre Verzano but Danna was always alive. Also, even when choosing to defend Verzano from her and killing her a second time, upon exiting the building and talking to Pallegina, she thanks me for getting rid of Verzano (which seems bizarre since I had nothing to do with it). I then reloaded another save from about 2 and a half hours previous, before I had even started the quest. I picked up the quest, killed Danna again in the Goose and Fox Inn, went back to Verzano, and still had the bug occur. Hopefully somehow this information will help tracking it down.