Phalangite armour?

One problem with missile combat was the fact it was pretty poor at actually routing people. You could totally decimate helpless units with extended fire, and the survivors still stood their ground. Which is of course why it was very rare for anyone to rely solely on firepower - pretty much everyone had or developed some proper shock arm to charge and break such shredded and dispirited formations which would nonetheless have taken ages to entirely reduce with missiles.

I'm playing sauromatae and in fighting selukia I have trouble killing 3 phalagites (medium or heavy) with 6 units of horse archers without running out of ammo. I even restrict firing to their backs, even still I can only reduce them by half through missile fire, after that I have to use hit and run chargers to finish them off. Still, I appreciate have some challenge, I still decimate selukid armies when the computer calculates odds such as 1:2 or I think 9:40 was my best when I used 120 horse archers to kill 800 selukids(5 phalagites + support). I was even unhappy with myself because I took 27 casualties that battle. I think the extra armor as well as the cohesion and professionalism of the phalagites is appropriate and realistic, and without it certainly battles against phalagites using nomadic factions would be way too one sided.