Quote Originally Posted by Brave
Cav are higly powered anyway, normal formation is sufficient to flank.

Ah yes, but wedging can allow even your light cavalry to get the extra punch they need to route an engaged unit. Knights are fine in close formation, probably Mounted Sergeants too, but Steepe Cavalry and the like lack a little impact against aroured troops. Putting them into a wedge lets them do the damage they really need to. Driving a wedge of anything into someones back is always good, but getting some melee value out of your missile or light cavalry is great. Besides, if they have low defense, they're going to die fast anyway, may as well get some more kills from them and hopefully Rout the enemy faster.