Cavalry - Before the Marian reforms, the Roman cavalry were the aristocratic Equites - light cavalry used mainly to pursue fleeing enemies. After the reforms Roman cavalry was made up of auxiliaries taken from horse-familiar tribes. You've got decent armor and weapons plus a horse, but you're still not in the spotlight...Roman tactics mainly have cavalry harassing enemy formations and chasing fleeing soldiers while the infantry does the real work. You seem to know a little bit about the Roman legions, but Gladiator and Rome: Total War aren't infallible.