Wowwee! Melee cavalry aren't garbage any more! They can actually perform very well against infantry who do not have pikes, as they should. Making them worth the additional cost/time of buying them warhorses, finally!
Testing in Battle_terrain_m, which is a reasonably open field with some small hills, good for cavalry:
* 60 T5 Champions against 60 T5 Elite Menavliaton - Champions won with 20 casualties.
* 60 T5 Vanguard against 60 T5 Elite Menavliaton - Vanguard won with 22 casualties.
* 60 T5 Vanguard against 60 T5 Legionaries - Vanguard won with 6 casualties.
* 60 T5 Cataphracts against 60 T5 Legionaries - Cataphracts won with 2 casualties.
* 60 T5 Cataphracts against 60 T5 Heroic Line Breakers - Cataphracts won with 4 casualties.
I also tested Veteran Faris. They don't have couched lances so they have to rely on just stabbing, which is still inaccurate for cavalry AI.
* 60 T5 Veteran Faris (hold fire) against 60 T5 Heroic Line Breakers - Veteran Faris won with 2 casualties.
* 60 T5 Veteran Faris (hold fire) against 60 T5 Elite Menavliaton - Menavliaton won with 3 casualties.
I also tested cavalry against pikemen. Worryingly, the cavalry beat the pikemen because the AI doesn't seem to understand that they need to brace their pikes when being charged by cavalry, even when they are on defense!
* 60 T5 Champions against 60 T5 Pikemen (offense) - Champions won with 5 casualties.
* 60 T5 Champions against 60 T5 Pikemen (defense) - Champions won with 11 casualties.
So we still aren't where we need to be, but regardless, this is a big improvement. We are rapidly approaching balanced combat and Good Tactics™.