alright, gonna write this out proper, since it seems to actually be generating discussion:
Current Cataphract:
Byzantine unique knight
unlocked at Chivalry
200 , requires horses
28
CS (+4 from Knight)
3
moves
can move after attack
-25% reduced city penalty (down from 33%)
Open Terrain bonus (+30% CS in open terrain)
does NOT have ignore terrain bonus (ie. benefits from hills, forests, etc.)
New Cataphract:
Persian unique Horseman
unlocked at Military Theory
100 , requires horses (+10 from horseman, but still -25 below war elephant)
15
CS (+2 from Horseman and -1 from Elephant)
3
moves (same as Elephant)
can move after attack
does not benefit from terrain defense
-25% reduced city penalty (down from 33%)
Armor Plating II (+25% defense, the not-obsoleting one)
With both the terrain bonus and the bonus in open terrain, that approximates a single bonus that gave 25% or 30% defense in any terrain and +30% on attack in open. It's a weird collection of interlocking terrain bonuses that provide complete coverage, and the Immortal's existing 25% on defense approximates the same effect without all that complexity.