Units with both spears and swords

[mcantu]

I think the only reason Spears have a bonus vs. cal is because they can PUSH the soldier off the horse, in real battles the guy might survive if he's strong, and may even get up and fight if he doesn't have any broken bones..but RTW can't do that so its just +attack

and horses (trained or not) do not like running into a wall of pointy sticks...and once a charge is stopped, its very easy to reach the soldier on a horse with a spear and be far enough away that he can hurt you

[Philippus Flavius Homovallumus]

The other big advantage with a spear is that it keeps you out of reach of the horse's hooves. As to the knockdown thing, think about it. Knock a guy off his feet and he'll probably drop his spear, when he get back up he draws his sword.