I managed to do it a few minutes ago after an hour of failed attempts:
[video=youtube;Ur0v995qrVA]https://www.youtube.com/watch?v=Ur0v995qrVA&feature=youtu.be[/video]
What I found out is that there is a rather easy way to dodge the Spell Weaver`s spin attack. At first the Blizzaga spells hurling above you damage you if you try to jump, but if you wait long enough they will vanish and then you can exit the vortex by doing an double jumping up and then using an air dash. There is just enough of a window for you to get back to Mirror!Aqua and land two combos.
The Dark Blizzaja attack might be hard to dodge, but you can actually stop Mirror!Aqua using that with a well placed Thundaga. The moment you know she is using it that she telepots and says "You`r done". Then lock as fast as you can an use Thundaga. This reminded me of the Demyx fight in KH2FM, where you can stop him at using some of his more annoying and harder to dodge move by using a well timed Thunder spell. That made me beat him eventually at my LV1 run.
When she splits into clones that talk about Aqua`s fears, I usually cast Thundaga and locked on to the real one that was stunned. You have to be fast thou.
Everyone else also gave good tips, just try and try and try again, and once in a while you`ll probably have some luck on you`r side. You can do it! I hope this helps.
God dam I love this boss so much, even the Super version in the Zodiac mirror that I managed to beat too today. I am really enjoying 0.2.