Flaming sword vs regeneration

Question

I am trying to determine how lethal vs nonlethal damage works against regenerating creatures when you are using a magical weapon with the flaming ability.

Reading the regeneration monster ability it says

Damage dealt to the creature is treated as nonlethal damage.... Certain attack forms, typically fire and acid, deal lethal damage to the creature, which doesn’t go away. The creature’s descriptive text describes the details. A regenerating creature that has been rendered unconscious through nonlethal damage can be killed with a coup de grace. The attack cannot be of a type that automatically converts to nonlethal damage. An attack that can cause instant death only threatens the creature with death if it is delivered by weapons that deal it lethal damage.

Would a sword with the flaming ability deal both non-lethal and lethal damage to a creature with regenerate? aka nonlethal from the physical sword damage and lethal from the fire damage.

Or does it just deal lethal damage?

Answer 1

Yes, a flaming sword would have some of its damage converted to nonlethal. Only the fire damage would be lethal. However, this does not run afoul of the bolded sentence—an attack with the flaming sword is not “of a type that gets converted to nonlethal damage,” it is if multiple types, and not all of them get converted. It would be unreasonable to disallow a coup de grace with one—though it would be reasonable to restrict the save DC calculation to the lethal damage dealt.