SO as the title states, is it possible to empower the Holy Sword Spell? so instead of gaining +2d6, you would get +2d6x1.5?
or would it be (2d6+5)x1.5
or would it be (2d6+5+damage from smite+ damage from specialization+ 1.5 two handed weapon strength bonus)x1.5 ?
I'd say no, in the same way that empowering a summon spell does not increase the HP or damage inflicted by the summoned critter. The effect of Holy Sword is to place the "holy" enchantment on a weapon (among other things), there is no variable effect to increase in what the spell does. The enchantment created by the spell causes extra damage to evil targets of the sword, not the spell itself.
The other reason it will not work is that the spell does not actually do any damage. What the spell does is to add damage to a weapon. The weapon is what is actually doing the damage not the spell itself. Empower spell only increases the damage of the spell itself. A good example is a magus using an empowered shocking grasp only multiplies the damage from the spell, they do not multiply the weapon damage or any bonus damage from things like the enchantment bonus of the weapon, or the extra damage from stat bonuses or feats.
I agree with Java Man's interpretation.
The spell adds the Holy weapon enchantment, which is not a variable effect of the spell.
another question then.
If you cast Holy Sword on a quarterstaff or other double weapon, would you say only one side is enhanced or both sides? If only one side, then it would be feasible to keep one side of the quarterstaff enchanted?
another question then.
If you cast Holy Sword on a quarterstaff or other double weapon, would you say only one side is enhanced or both sides? If only one side, then it would be feasible to keep one side of the quarterstaff enchanted?
Only 1 side.
However if you're using your Divine Bonded weapon class feature check out the DUAL ENHANCEMENT feat.
another question then.
If you cast Holy Sword on a quarterstaff or other double weapon, would you say only one side is enhanced or both sides? If only one side, then it would be feasible to keep one side of the quarterstaff enchanted?
Yeah one side only.
Which means you could enchant one side of the weapon and cast the spell on the other side.