Well crossed keys denote St. Peter because he was given the keys to the kingdom of heaven.
The padlock/heart shape below I`m not sure about but the unusual crown reminds me of something.St. Peter was the first Pope.
.I think the Holy Roman Emperor Charlemagne , sometime about the ninth century but some Rootschatter may be more accurate.
What is the object it is on, it looks like Pewter.?
Viktoria.
P.S.I did not read the post, now I have one thought I had seems a bit likely and that is The Kingdom of Bavaria. I gave away all my books on Ludwig and his castles but a little bell is ringing
=it is that crown-,the family were Wittelsbachs, a notoriously mentally unstable family.
Sisi, the Empress Elisabeth of Austria and mother of Crown Prince Rupert of Mayerling notoriety wqs Ludwig`s first cousin
How interesting-hope you solve the mystery. Viktoria.