Divine Shield
( Defenders of the Faith: A Guidebook to Clerics and Paladins, p. 19)[Divine]
You can channel energy to make your shield more effective for either offense or defense.
Prerequisite
Power Attack (PH) , Improved Shield Bash (DF) , Ability to turn or rebuke undead, CHA 13+, STR 13+,
Benefit
Spend one of your turn/rebuke undead attempts to channel energy into your shield, granting it an enhancement bonus equal to your Charisma modifier. This enhancement bonus applies both to the shield's attacks and defense, and lasts for a number of rounds equal to your Charisma modifier.