I am uncertain as I cannot read the script. However if I were to take an educated guess the one on the right may be the Emperor Constantine the Great who is credited with founding the city that bore his name until about a century ago as the Capital of the Eastern Roman Empire. The figure on the left may be the Emperor Justinian I who built the Hagia Sophia. Justinian is not generally recognized as a saint but the halo was commonly applied in those days to all depictions of the Emperor.
Sounds like a plausible guess. I know so little about the history and culture of the Eastern Church but I am fascinated by the fragments I encounter: your contributions are especially appreciated.