I dont know researches, but you cant get researches accurate, just close. And similar researches give mostly similar results, which vary depending how lucky you were in companies fighting in battle calc. So i doubt they are 1/8, atleast from my experience playing in first 3 eras.
Well, about melee i'm sure, because olsi blundered and didn't send his army to defend. So we had battle report with a clean siege, without archers inside. In this case melee is easily found and is exact. I tried to calculate armor from my battle and there values were around 7-8 (of course considering a fixed melee 1).