I'd also like to see that, considering the round shields are horrible cav and drop dead quickly. Long shields require modding to get although they should be there for Spain.

Are you referring to general cav? Faction leader and faction heir general cav units with some valor can indeed rout whole armies.

To make the shock cav attack work, have the cav with strong charge hit the enemy infantry from multiple directions simultaneously.

This requires very high charge/attack cav and awesome timing. Mass is also key as is near perfect timing.

Macedonian light lancers for example are great and 2-3 units hitting a hastati unit simultaneously from all directions can instarout it. Howeve,r I do not see any cav other than general cav or maybe longshields doing so with Spain.