A caution warning about lethality: it's a bitch to balance. I would say use lethality to differentiate weapon type like projectiles versus good weapons versus simple peasant weapons, don't use it for slashing/piercing/blunt. Also, the type of skeleton you use will also determine "lethality" as some skeletons attack faster than others. The fastest is fs_2handed, then fs_swordsman, then fs_dagger, then fs_spearman. So use lethality if you don't want, say, a simple dagger-wielding peasants pwning a spearmen unit (assuming their attack and armor are close).