I had my legendary sword by the end of day 6... after a couple of tries :)
Graphics: I gotta say- the swords looked cool and the menus were readable. It would be cool, if you had a constellation picture on the button, not only the name.
Audio: no audio :( Some blacksmith sounds and medieval-style music would do a lot for atmosphere.
Gameplay: I had fun! I played the game to the finish and I see potential here.
Theme: I liked how the constellations were at the heart of the game. I didn't like that it took me a second to figure out this were constellations and not spells or elements :)
Over all- lots of potential here. Could be elevated just by adding small elements like sounds and some background graphics (maybe a blacksmith workshop). Also- if, instead of picking the constellations from the menu, I could pick them from the sky. What I'm trying to say, is that you are onto something here. Keep it up!