Greek Orthodox Churches' flag modified to resemble the emblem of the Ecumenical Patriarchate of Constantinople (1261-1453).
Note: the original author did not write what he derived this image from; however it seems clear it is a modification of File:Flag of the Greek Orthodox Church.svg with the sword on the left foot replaced with a cross in order to look like the emblem of the Ecumenical Patriarchate.
Own work
Dragases (talk)