You are trained in how to properly use a shield.

<php>echo “<b>Benefit:</b>”;</php> When you use a shield (except a tower shield), the shield’s armor check penalty only applies to Strength- and Dexterity-based skills.
<php>echo “<b>Normal:</b>”;</php> When you are using a shield with which you are not proficient, you take the shield’s armor check penalty on attack rolls and on all skill checks that involve moving.