Late Roman Army Grade/Rank List under Anastasius

[Nathan Ross]

I seriously doubt that an official Sermio by an Emperor, erected in stone for all to see, would be dedicated to a legion of the limitanei, would such a low class legion warrant this sort of thing?

Possibly not, although the emperor's writ was required to be everywhere omnipresent! If such a ruling had been made about a limitanei legion, wouldn't they want to commemorate it?

A palatine legion, on the other hand, was a mobile force - why would they have erected this monument (which they would have wanted to refer to regularly) in such an out-of-the-way place as Perge?

So either option is possible, I'd say. Many of the rank/grade titles from the inscription also appear among later limitanei units in southern Egypt.