Note that the Mend Armor effect may be used with any specified value. When casting it as the second level Celestial spell, the value is set at 20.
Example: Ena has a suit of armor which has been evaluated at 20 points. She is in battle against two enemy orcs, one of whom has landed hits for a total of 12 points of damage. Ena is starting to get worried about her armor. Fortunately, her ally Belthivis is nearby and leaps forward, touchcasting a Mend Armor spell for her. Now that her armor is back up to its full value, she feels much more confident against the orcs.
This ability will not work on a suit of armor which has been completely destroyed, such as a mundane suit of armor that was affected by the Shatter ability.