A great defensive shield, Gerke's Sanctuary is a good option for physical fighters that prefer defensive bonuses to offense.
Gerke's Sanctuary has the highest chance to block out of all unique shields. Not only Paladins, but all classes can almost max out their block by using Gerke's Sanctuary. This and its high defense make Gerke's Sanctuary a sanctuary indeed.
Additionally, Gerke's Sanctuary gives a boost to all Resistances. Due to the lowered resistances in Nightmare and Helldifficulties, it is generally good for any shield to have this property.