That mask does indeed belong to Middle Ages Roman "cataphract" (many of you still call it false as Byzantine).
But that mask is from middle 10th century (Nikephorean Army reforms) and is heavily influenced by those masks of Khazar equipment!!!
10th century "cataphract" equipment evolution.
East Roman empire in Attila era, DID have helmet masks though but they were much more decorated but also much more rare!
The sassanid infuence could be full head chain cover for anly few soldiers and definatly not archers!!!
Roman cataphracts of that era!
Eastern Roman cataphract from 3-4th century (in this point his helmet sugests eastern influence)
Compare the Roman Cataphracts (all in the east part of the empire) with the Armenian one of the same era!
This guy has more Roman than Sassanid influences in his equipment!
But this Armenian in the same era have almost only Sassanid influences in his equipment!
LINK
Roman Infantry:
German allied troops (Allemani) 4th century:
Actually masks used mostly by eastern cataphracts like this Sassanid
This is HOW cataphacts used their lances (mostly made from imported baboo)
For last this is the most famous picture of Roman Cataphracts!
EDIT: IF CA 3d modelers are not capable to create accurate Roman equipment i sugest them to seak HELP from that mod !!!!
Razor with the help of Leif Erikson provided material that this mod's team made an exelent result!