It should give + to diplomatic relations. A lot of retainers is underused in their possibility to add both buff and debuff with the same retainer so youll never chose certain retainers as theyre only debuffs.

its basically unlucky charm indicating that you can pick only one but pros like +fames shouldve had been added

Yeah, I was always curious as to why a developer would think anyone would choose something with absolutely no buffs over something that would.