I be wanting to know how do I catch my sword on fire to do more damage by fire. I not know the right words. And just putting it in the fire not work so great either.
Or maybe coat in oul, lite it and hope for the best?
Though the Aura is the best option--the base scroll normally goes anywhere for 13g+ but you could get an expanded enchantment and give it 1:d elemental aura for more limited duration.
The sky magic is fickle. Me cannot make this decision for you more than me can will your arm to move. You must learn how you see the sky. Personally me think that seeking an Earth Aura sword may be more worth your time. Undead are more common anyway.