Proficiency

A character who uses a weapon with which he or she is not proficient takes a -4 penalty on attack rolls.

A character who wears armor and/or uses a shield with which he or she is not proficient takes the armor’s (and/or shield’s) armor check penalty on attack rolls and on all Strength-based and Dexterity-based ability and skill checks. The penalty for nonproficiency with armor stacks with the penalty for nonproficiency with shields

Weapon, armor, or shield proficiency may be granted by the character's race, class or by the following feats:

• Armor Proficiency (Light)
• Armor Proficiency (Medium)
• Armor Proficiency (Heavy)
• Exotic Weapon Proficiency
• Martial Weapon Proficiency
• Shield Proficiency
• Simple Weapon Proficiency
• Tower Shield Proficiency