Parry Ability skill
The Parry Ability skill is what dictates your character's ability to fend off an incoming melee or pole-ranged attack with the weapon in your right hand. Characters usually cannot parry missile attacks, nor can they parry an attack with a missile weapon.
Parry is affected by Reflexes, current weapon skill, and current weapon balance. Attempting to parry with a poorly balanced weapon or a weapon in which you have few ranks in will be less successful than parrying with a well balanced weapon or one you have many ranks in.
Parrying also teaches some of the skill of the weapon you are parrying with. Example: If one were to parry with a longsword one would gain experience in the Heavy Edged skill in addition to Parry.
Spells and abilities that boost Parry Ability
Spells and abilities that decrease Parry Ability
Parrying Missile Weapons
Paladins and Barbarians have the exceptional ability to knock aside bows (and functionally parry the shot) if the shooter fires within the range of the parrying weapon. To be successful they must have some defensive stance points allocated to parry.