Re: Tenmporary Weapon Enchantments
Hmm, I'd probably go with a partially limited power for the demonslaying spell. I'd make the spell as extra HKA damage with the demons only limitation, and whatever other limitations are needed for spellcasting procedures. I'd use the Lingering advantage from Fantasy Hero to make it last a certain amount of time.
Golden Sword: +3d6 HKA, Lingering: 5 mins (+1), (AP 90); Demons Only (-1 1/2), RSR: Magic (-1/2), (RC 30).
If you don't have Fantasy Hero, you could use continuing charges or uncontrolled instead of lingering.