An escutcheon is:

A shield

An emblem

A protective plate

The hardware surrounding a keyhole

A surface through which a conduit may safely pass

And, under certain circumstances…

Wait. No. That's enough. You don't need the rest yet. What you do need, is the gesture! Place your hand over the center of your chest.Trace the sign as instructed. X MARKS THE SPOT. And remember these three things; The escutcheon marks, the escutcheon guards, the escutcheon permits safe passage. Should you find yourself in immediate danger during transit and experience the overwhelming conviction that you ought to remember something about the escutcheon, GOOD.

Very, very good.

Personnel considers further explanation counterproductive at this stage.