“ A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for study by the Guild. The party's presence will be 'requested' for this expedition.”
“ A culture must hide its hands in the arm of their clothing as a sign of respect and peace. When approaching somebody you show them respect by crossing your arms and hiding the hands in the shirt sleeves. Nobody worries about hidden knives and such, it is the threat of magic that this custom was created to prevent.”