Kaiser Heinrich:

*sotto voce* Always with the nitpicky types, always. Can a Kaiser never catch a break around here?

*out loud* You cannot possibly expect me to allow anyone to retain a Duchy who did not side with me from the beginning or did not willingly defect over to my side. I will not get into a pointless legalese battle when the implications of my negotiations were clear. You will become the first vassal of what promises to be a very strong Duchy as well as a landowning one - a very good opportunity to springboard your career.