Proficient

Being proficient with a weapon, shield or armor means you can use it without incurring the non-proficiency penalties. Proficiencies are obtained through feats, either given at character creation or during advancement.

Proficiency feats

 * Simple Weapon Proficiency
 * Martial Weapon Proficiency
 * Exotic Weapon Proficiency (requires base attack bonus of +1 or higher)
 * Light Armor Proficiency
 * Medium Armor Proficiency
 * Heavy Armor Proficiency
 * General Shield Proficiency
 * Tower Shield Proficiency (requires General Shield Proficiency)

Non-proficiency penalties

 * Gives -4 to attack rolls if not proficient with weapon.
 * Applies Armor Check Penalty to attacks and skills if not proficient with armor or shield.
 * Any class, such as pure-breed rogues and arcanes, can use a shield with 0 armor check penalty and suffer no attack penalty.
 * Mithral/darkwood heavy shield has 0 ACP.
 * Mithral light shield has 0 ACP and 0% ASF.