I don't have much experience using skirmisher cav in M2, is this an engine issue? I noticed that the missile stats for these units are reasonably high, but the javelins very rarely cause casualties. Mostly I use them to tie up the enemy cav in melee.
Recently one of my client kings in North Africa was attacked and I wanted to confirm. I had several units of local skirmisher cav, several units of foot archers, a unit of slingers and a couple of units of leftover infantry from Italy. The enemy was almost all skirmisher cav and I decided not to engage in melee. The enemy's skirmisher cav stupidly bunched up into a ball, making them a good target for missiles. My archer units got from 90-125 kills, and my skirmisher cav units got around 20-30. This was a long battle that ran about 3/4 of the way through my time. In a "normal" battle where the skirmisher cav are supporting infantry, they would get next to no kills with their javelins.