Unfortunately the only Armenian kingdom that has tons of pictoral references is the ancient period kingdom (Urartu 850-590BC). However, these are pictures of what an Armenian general probably looked like. They are scenes from Vartanantz, which ended in the Battle of Avarayr between Persia and Armenia in 451. The general is Vartan Mamikonian.
Unfortunately that is all I can find in terms of pictoral sources.
EDIT: Here is a link to the thread where a mod for MIITW, The Gathering Storm, is creating an Armenian faction from the same time period (395AD).
http://www.twcenter.net/forums/showthread.php?t=107385
EDIT2: Also, the capital of Armenia should be Dvin, not whatever it is at the moment (Taran?), and Armenia should have control of Van I think.
EDIT3: One last tiny thing, the Arkah should not be Artashes, but Vramshapouh (reigned until 414). Vramshapouh's eldest son was Artashes, but the person who inherited the throne from Vramshapouh was the Persian prince Shapur. The Nakharars overthrew Shapur and put Artashes on the throne, but Artashes was a bad king apparently according to the histories.
I hope this helps as well!