Well I noticed that in the later expansions they have been adding keywords to spells contained in Mage abilities. See Forcemaster and Warlord for example, so that these can interact with other equipment or effects. I also noticed that they added Mana to the subtype on the Moonglow Amulet. This made me wonder if Holy had just been left off of the quick spell description for this Priestess only equipment.
Thanks.