True, but when you have two 4th level spell slots, which is a very high level paladin I will admit, then you can have a holy sword and divine sac, which is just nasty amounts of damag.e
Actually I just thought up another question, would holy sword double the sacrifice damage as well?
Unless Holy Sword mentions that it also doubles the extra damage from, for example, the Flaming property, it would not double the extra damage from Sacrifice.