I feel like that Byzantine art tries to circumnavigate the graven image issue by only depicting images pulled from descriptions in the Bible. As well, the use of Icons was a way to not violate the Second Commandment, as an Icon was seen as a holy object, not a reproduction of a person or being, which would make it a false idol of sorts. Instead, these images were a way to draw people closer to their faith, and the church at the same time. This would explain why there are so many icons of the Virgin Mary from this period, as the idea of Mary would draw people into the faith.
I hope this all makes sense. This is a tough subject for me, as I seldom get and understand religious imagery, either in art or in literature.