how do vital strike and sacred weapon interact with one another?

[fel_horfrost]

If you take vital strike at 6th level warpriest and used spiked gauntlets as his sacred weapon what would you double?
The 1d4 for the gauntlets or the 1d8 for his sacred weapon damage.

[Nefreet]

It would be 2d8 plus modifiers.

[mplindustries]

The weapon's base damage is added again. In the case of a Warpriest with sacred weapon, the base damage scales with your level, so you'd be dealing an extra 1d8 at 6th.