Most magic armor and shields only have enhancement bonuses. Such items can also have one or more of the special abilities detailed below. Armor or a shield with a special ability must have at least a +1 enhancement bonus.
See the complete Magic Armor and Shield rules for more information.
Three times per day, the wearer of a suit of armor with this ability can cause the next creature who hits them and causes damage – whether by physical or magical attack – to take an equal number of points of damage of the same type.
Source: The Book of Divine Magic
Three times per day, the bearer of a shield with this ability can create a shimmering golden dome of 5 ft. radius. Undead creatures are unable to physically enter the dome, though they can still attack you with ranged weapons or targeted spells. Living creatures (friend and foe alike) and constructs can enter the dome without problem. The dome will remain in existence for 7 rounds. Any attempt to move at more than half your normal speed, or to take more than a single attack, while the dome is active will end the effect.
The Book of Divine Magic. Copyright 2009, 4 Winds Fantasy Gaming; Authors Connie J. Thomson and Robert W. Thomson, with Katheryn Bauer and Sean O’Connor.