Late Roman Army Grade/Rank List under Anastasius

[Marcel Frederik Schwarze]

This document is not an 'effective strength' snapshot like the Dura papyri or Vindolanda tablet - it's an official list, carved into stone, telling us exactly how many men were supposed to be in the legion, and intended to stand for some time.

but the slab only tells us about the number of soldiers in this so called Legion. There is no reference at all to a widespread validity here. On the contrary, there seem to have been such local abuses that Anastasius felt compelled to set up the slabs or tables at this point and in this city. Whether such troop-lists have been set up at other locations as well, has to remain speculation so far. And if so, then perhaps with other figures.
Just few years later, when Justinian raised the throne, new regiments were just numbering round about 500 men.

I cannot deny the possibility that a normal legion had a small corps of cavalry in the late 4th, 5th or 6th centuries, let's say messengers, officials and some guards. But a mounted group of such a high quota compared to the infatry has nothing to so with a legion in the late antiquity and transition periode: as already described roughly 1000 : 300.
Also the gap of annona given to the higher posts compared to the lower posts is not big enough to speak about a classical legion. We know that the gap of allowances in auxilary units between soldiers and centurions was indeed much smaller compared to the legions.

The best essay to understand the very early numeri and its evaluation is still that of Marcus Reuter (also Nemeth is good, but Reuter is more extensive).
XXX see Studien zu den numeri des römischen Heeres in der mittleren Kaiserzeit. In: Berichte der Römisch-Germanischen Kommission 80, 1999, p. 359-569 

Most of the allegedly barbarian numeri in the 3rd century were auxiliarian vexillations (cohortes et alae). That means they were paired with other auxillaries and sent away from the parent unit. Just a small number of numeri was of real barbarian origin - the so called ethnic or national numeri. But even the latter group was according all studies quickly absorbed or integrated into the roman system and many of those numeri were indeed mixed with infantry and cavalry.
The cavalry of the numeri at Kapersburg and Nidensium were called "veredarii". The cavalry of legions and cohortes equitata had other names.

Then a last word to the deputatii.
a) they were most likely field- or combat medics, as described in the Srategicon (by Mauricius) and Tacticon (of Leo VI.). They were dressed in a light way, sometimes with horses and stirups for two people.
b) also factory specialists (e.g. smiths) were called like that in the same time frame. Specialists who were sent from the weapon factories to the troops - to explain how to use machines or to describe new developed technics when making new weapons etc. also called deputatii.
And indeed, by reading some tales of Procopius and others one get the impression that those factory-specialists were travelling on company business - and there was a high traffic of technical staff between all the roman troops and the factories.
But since our deputatii are grouped together with Military chaplains, and the list is made for the constantly present staff, it makes sense that they were deputies of the first group, and acting as combat medics as well.
In both cases, as fabricienses or medics - they were unarmed and for sure not integrated into the active compat groups of the centuriae or turmae. (as others as well, e.g. librari or the other handcraftsmen). Also the Armaturae Duplares and Semissales are probaly forming a schola of instructors. If they stood in a row with the other fighters is debatable. The Optiones are writers and belong to the administrative staff of the numerus like the actuarius or chartularius in other regiments.