That's a pretty cool concept !
I like that you can access to upgrades anytime you want to improve your character when you have enough crystals, and the charcater model itself is really well done, and i also dig the detail that every shield blade you add is visible on your outfit ^^
and for a game jam that map is huge O_o but i do like that in a way since you have to walk a lot it helped showcase tha cool day/night cycle transition.
i fell there are some rough spots though, the aiming felt a bit weird as the blades seemed to fly over or under the targets and only hit when they travelled back, this was particularily odd when on slopes and to fight the boss, and also too bad there were no sounds what so ever :(
Regardless of this, this feels like a solid proof of concept and you could totally expand on it and make a full game
Well done :)