+400 to Armour while affected by a Guard Skill Buff
Regenerate 1.5% of Life per second while affected by a Guard Skill Buff 
Adamant is a notable passive skill that grants increased armour rating,as well as additional armour and life regeneration while under the effect of a guard skill. It also grants a chance for double armour effect when hit. Enemies are also less resilient against your physical hits.