I love it! The only thing I'd criticize you about is that, Being a Member of the Brachati Seniores (The Shield Image you are clearly trying to depict), he should be wearing a chain or (considering the fact he's an eastern empire soldier) possibly a scale hauberk.
From what I know Brachiati Seniores were part of the western field army not the eastern.It's questionable to which extent scale armour was more in use in the eastern army then the western one and soldiers often fight without any armour at all,for example if there was need for their greater mobility or if they were not to be expected to fight in the front ranks.Also there were fashion in the later era to wore clothes over armour.
Ah my mistake, and yes armor was often determined by what the people knew how to make - Roman Chainmail originated from Gaul, so it's most likely the Armies of Gaul wore chain because it's what they knew how to make. The People in Syria were accustomed to making scale, so Armies in syria probably wore scale.
I don't know of any exidence in the late Roman era to wear clothes over armor, but it is indeed true that units had both SKirmishing and non-skirmishing troops in the unit. What's generally believed is that you'd have about 4 Maniples (or Numerii, there is evidence to suggest that the Numerus was a replacement term for the maniple in the 5th century and was led by a Ducenarius) of Main-line heavy infantry, accompanied by 2 maniples of skirmishers (armed with Veruta/Lancaeae or the Bow)
Very Nice. I always appreciate attention to the details of material culture in illustrations of ancient historical subjects. We need more illustrators that cover the classical and late classical period.