In case you might be interested, other icons I've read of or seen pictures of on Russian banners would be, besides Christ, the Madonna and Child, Saint Michael, and Saints Boris and Gleb.
One could use wargaming flags or try using a copier or printer to reproduce icons in books or from the internet, and reduce them to the appropriate size. Naturally one would want to select Orthodox icons or Byzantine ones. A friend of mine did just that once for a unit of Napoleonic Russian militia and it looked surprisingly good.
I would guess that the icons would be stiff, with cloth tails fluttering in the breeze. I did see a picture from an old manuscript depicting a battle between Novgorod and Vladimir (I think) where an image of the Madonna and Child was held aloft like a Roman vexilla.
Many thanks for your response. You are apparently a better Catholic than me. Now that you mention an angel, I can see the outline of it and it makes perfect sense. I think you are right on this. Any one out there with a different theory? Again, interesting story on the banner. I don't think we are off the topic here. I'm always glad to learn a bit of history through these "toy soldiers/scale figures" and have this forum to exchange information and ideas.
Thank you Dave C. for your suggestions on paper flags. I usually do not use paper flags on my figures (to cut down cost)and try to do it by hand. They're definitely not as pretty, but it gives me a another kind of challenge and I am still trying to improve my painting skills. As I said previously, I am going to paint this as is straight from the box with no modifications.