What happens when you put both weapon enhancements on a sap? What happens when you add sneak attack damage to the weapon as well?
What happens? You have a magical sap that deals 5d6 nonlethal damage to your opponent and 1d6 nonlethal damage to you. Neither Sapping nor Vicious change the damage type, so it's always the damage type of the base weapon: nonlethal bludgeoning.
If you sneak attack successfully, you add your +Xd6 nonlethal sneak attack damage to the sap's damage, just like you always would with a successful sneak attack using a nonlethal weapon.
I agree with DM Blake, but the damage caused by Vicious is lethal to both you and your target. Vicious is non-typed energy damage, not weapon damage, and is always lethal unless specified otherwise such as the Warpriest greater war blessing.
Yeah, I could go with that too.
Yeah, while they don't say vicious is lethal, I assumed it was always lethal damage. It would be easier to soak if you could turn it non-lethal.