CWK weapons mystery, where is the end of storyline?

btw theres no story, you just go on PQ , finish , go out and that is it, where is the demon? how the keep got ruined this way?

I think the story is contained within the Jack NPCs during the PQ. You don't exactly have time to read them, though. (For example: If you stop to read the last one, you must sacrifice your bonus.)