Fun game! I like it! The theme really works, and the gameplay is solid.
I like the upgrades. I felt like a really lousy hero at first, getting stun-locked by the rocks. But after a bit, I felt really powerful. I think the shield should block stones at the beginning, I felt like the block was useless and forgot about it.
I think shorter, beginning levels would be a good addition, and I think raising the price of the more interesting potions would be an improvement too. I bought all the fun stuff immediately, and then just spent the rest buying speed/health. Maybe you could add a potion that reduces the amount of stun you get when you get hit? Or maybe an enchantment that makes your sword slashes bigger?
I also liked the intro cutscene!
Well done!