Sacred

Sacred
A suit of armor or shield with this quality assists only wearers who have the ability to turn or rebuke undead. Sacred armor or a sacred shield increases the owner's effective level on turn undead checks by 2.

This item enhancement was introduced with Module 3 as unique item enhancement only found on Chainmail Coif, named chest item found in Sands of Menechtarun. They added this to random loot table later though, and now they are common.

Can also be a bonus added to caster level for the purpose of turning Undead by the spell Seek Eternal Rest that stacks with Sacred items.