Radiant

The wearer of this kind of armor gains resistance 10 against energy attacks (acid, cold, electricity, fire, or sonic). The armor absorbs the first 10 points of damage dealt by any such attack, and this absorption causes it to radiate light for a number of rounds equal to the points of damage absorbed. This light is sufficient to illuminate a 60-foot-radius area.
If the armor absorbs more damage while it is radiating light, the newer radiant effect overlaps (does not stack with) the effect that was already in place. For example, if the armor absorbs 4 points of damage from one attack and another 6 points from an attack 2 rounds later, the armor radiates light for a total of 8 consecutive rounds. Likewise, if the armor absorbs 10 points of damage from one attack and another 5 points from an attack 2 rounds later, the armor radiates light for a total of 10 consecutive rounds.