My Hounslow Hangar has - along with a Passau Wolf latten - a date which actually corresponds to a local event in history:
This was the date of the crowning of the sixteen year old Lady Jane Grey, who reigned for 9 days before being subsequently executed.
Because it said ANNO 1553 I was convinced it was a date, but it was a century before Hounslow were making these swords. Did someone date their blade to declare loyalty even after 100 years?
Fascinating stuff to grapple with.