I think the only thing I use holy for now is to kill a mob we're wiping to at 1% (or to snipe a killshot). It would be fun to see it do higher damage (I don't think we'd be a threat to blms with the recast and mp cost of holy)... but I haven't tried much to make holy do more damage (I'll have to equip my mab earrings next time and see how much that raises the damage).