Thunderbrd
C2C War Dog
Spearmen usually have lower str than most other contemporary units but having greater ability against Mounted. Its a tossup what's 'better' but the upgrade works along the STR evaluation in this case. And its a change of weapon methodology that makes them take a step down from their anti-mounted specialism. Generically an Atl-Atl would be a better unit UNLESS against a mounted or animal unit.