The fact that it's a demon avenger weapon would mean 15% spell traces would be more effective due to HP gains. Also, 25% boss neb and then you can say this is an absolutely perfect item. Not taking anything away from the potentials though, I'm completely green in envy right now.
My DA's weapon happens to have 360 attack: 15 stars, fafnir and was scrolled with 15% traces. I find that to be more effective than prime scrolls.