Keeping casualties down

[athanaric]

A phalanx set reasonably deep (I use a depth of 6-8 men on huge unit sizes) in guard mode with its flanks protected will get insane kill ratios against almost any other unit: the only things that can really break it are a better phalanx or heavy cavalry.

[emphasis mine]
Apparently you have yet to get acquainted with these guys:

Spoiler Alert, click show to read: 

They can break a phalanx from the flanks or from behind and can inflict heavy casualties from the front. So a way to keep your own casualties down is to shoot these guys (or other falxmen) as soon as you spot them.

For Pahlava, the Indian guys are invaluable in siege battles (especially assault) as using them wisely will save you a lot of other, less powerful infantry units.