Also the game's lore prevents such a trick - Cure spells are actually water aspected here (hence the fluid-like effect when you cast them, and water sprites materialize around the caster when it's cast, it's what those glowing blue orbs are) - they're not white magic at all but conjury, magic that comes from nature (the elementals of the Black Shroud specifically), not a deity.

Hence, no 'holy' effect (also most zombies in Eorzea are actually created by an alchemical potion and are not 'darkness' aligned, so that wouldn't even work anyway).