Well the Iberians WERE the best light infantry, so that's no surpise. And while the numidians might look good with a decent attack/defense, it's misleading. Numidians have knifes for meele, and all knifes have high attack but just sad lethailty *0.04*, so they aren't as good as you think. Also, their defense comes almost 100% from defensive skill, so missiles will eat them up.