Board Thread:Theories Discussion/@comment-16798306-20130307124756/@comment-6946747-20130307213539

The only theory I have come up recently is this: Kachess Crim used the vessel of wrath with the purpose of killing Sateriajis. Kachess said that the vessel was a powerful object that could kill even a Demon. If you take those words literally, then he actually killed the Demon of Lust by killing Sateriajis with the vessel. I'm not even sure this can make sense, but I don't have any better theory...

But like your theory, AnimeApprentice and Octofan, that would make reasonable why there is a curse for the Duke's descendants. It could also be because he was the only sinner who had children, but I prefer first option -w-