phiuuuuu lots of thinking! Thanks a lot of course.
I have read that the first lines in battle were equipped with armour and those behind weren't, but I thought that this was achieved by spreading the "good" units on the front supported by "bad" ones. I didn't think there was actually so much difference in weaponry within the same unit!
The timeframes I'm interested are mainly the Julian era and the end VI beginning VII centuries; against the sassanians. Mmmmmm....:hmmm:from your words it seems they were completely different armies. Maybe I should concentrate on one timeframe only.
Sorry if my answer comes so late. I believe you are in Germany. If so we have 9 hours difference btw us.
Thanks again and good luck!