It's the feast day of Theodosia of Constantinople, who was executed after she knocked a man off a ladder while he was trying to destroy an icon of Christ. She exhibits a degree of severity that you usually associate with the iconoclasts. There's something of Michael Corleone about her. That gesture of her right hand, normally meant as a benediction, looks more like, "Hey, you just watch yourself."
This icon of the iconophile is housed at Mount Sinai Monastery, near where God told Moses, "Thou shalt not make any graven images." Watch a documentary in which a monk ruefully makes this very point.
Christian iconography developed directly out of Eastern Mediterranean pagan iconography. The Louvre has an Egyptian shroud painting in which a woman holds the same pose as Theodosia, except that she's holding an ankh in her left hand.