Shield jab, helpfile vs. reality.

The helpfile sais it will work automatically for a paladin who has mastered the use of the shield. I took this to mean a paladin who has practiced the "Shield mastery" skill. but, at rank 15, before I even have the "shield mastery" skill available, shield jab is going off during combat. My shield block is only 81% 'SHIELD JAB' By striking an opponent with a quick swift thrust of the lip of the shield, it is possible to knock them over. While size and strength allow for a more forceful blow to be struck, speed and agility are what create the opportunities to begin the maneuver at all. A paladin who has mastered the use of his shield will do this automatically in combat.