Why this stemma was not used in Pope Benedict's election?
What does this mean?
This was rather unusual. It must be kept in mind that when Pope John Paul I was elected in August, 1978 the banner still had the coat of arms of Paul VI. Since John Paul I lived for only 33 days they were in the middle of changing the banner and simply left it in this "empty" state until the election of the new pope. There was a similarly empty shield (with a white field) hung above the papal chair at the Installation Mass of Pope Benedict.
Wow... this picture clarified a question I kept in my mind for the longest time! I was curious to see if during the first blessing of Bl. JP II the old Montini coat of arms was still used, or if they had replaced it with the one for Papa Luciani. I guess this solves the riddle, since all the videos I could find had the lower section of the balcony out of camera...