Just found the reference. The grouping is called the Tetrarchs, presumably representing the four Tetrarchs of the Roman Empire that existed in the late 3rd and early 4th century. The Empire was divided into four jurisdictions, ruled by four co-equal emperors - Tetrarchs (tetra is from the Greek for "four"). There are actually four figures, but they don't seem to represent anyone in particular since they are all the same.
The swords would then probably be either some sort of badge of office, or a very decorative style. The eagle was the symbol of the Roman Legions, and they seem to be wearing some sort of crown.
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