SRD:Exotic Weapon

Simple, Martial, and Exotic Weapons
Anybody but a druid, monk, rogue, or wizard is proficient with all simple weapons. Barbarians, fighters, paladins, and rangers are proficient with all simple and all martial weapons. Characters of other classes are proficient with an assortment of mainly simple weapons and possibly also some martial or even exotic weapons. A character who uses a weapon with which he or she is not proficient takes a –4 penalty on attack rolls.