When looking at Atum's Protection on the reward screen for a quest, the item doesnt display it's ability or allow the user to hold shift to see what the ability does. Ability and shift to display description show when you obtain the shield and the shield works as intended otherwise.

Atum's Protection normally is a shield that provides the ability "Consecrate" which "Ignites and damages undead when you block their attacks"

All other Atum reward items show their ability and description.