Wissembourg - Saint-Pierre-et-Saint-Paul

Outside the choir of Saint-Pierre-et-Saint-Paul is this kind of "plaque". The graffiti is the hand.
Via the words below it is tried to find an explanation for this pointing hand.

It reads "HIE VOR IST DISS GEMICHET", what means "here it was done" or "here it happened".
Actually nobody - today - knows what ever has happened here.