[SirJohnBarleycorn]

I agree, it does look Byzantine.

The bottom figure does indeed to be wearing the garb of a Roman legionnaire, and I wonder if that is not intended to be Constantine. The problem, though is that the figure under the horse looks moorish to me, which would be anachronistic.

Here is a statue of Constantine:

The top figure appears to be Christ.

The second row could be a bishop on the left, and a Christian King on the right (Charlemagne?)

[Jet Jaguar]

Perhaps the expert, Technical Editor, could tell of its’ authenticity?

[Ramius]

Charlemagne is who I first thought of as well, for that figure on the middle right.