So a friend of mine has brought up an interesting conundrum.
If a magus has Merciful on his sword and delivers a spell through his sword, does the spell's damage then deal non-lethal damage from the Merciful ability?
I would argue that, no, it would not, given the enchantment is attached to the weapon and not the spell. Doesn't seem to jive, if you ask me.
Can anyone confirm or deny my friend's assertion?
You are correct, the spell is a different damage source than the sword itself. If you use Shocking Grasp with spellstrike, the sword does its' damage, and the spell does damage of its' own. If the target had DR to the sword, like if it were a Mummy, it would not apply to the damage from Shocking Grasp. The same way if a target had electricity resistance it would apply to the spell but not the damage from the sword hit.
The Spellstrike ability also states that on a critical hit, the spell only does x2 damage, and not the crit multiplier of the weapon, say if it were a Scythe that does x4. The spell damage and weapon damage are 2 different sources of damage. They aren't 1 combined source.
Thank you! I thought as much.