This is an excellent example of the kind of realism that adds no value to the game.
A scripted spell that plays a sound on the NPC, while reducing their confidence and personality? No problem.
Yep that could work. Now imagine the guy in the Mages Guild responsible to keep a log of all user-created spells the mages do in his lab.
(Actually, you can use the "Fear" in-game spell and just rename it. )
Sometimes I like to think of what the developpers say at lunch breaks about some of the strange and useless game features suggested here.