Randomness kills it for me-
The concept is great but as others have pointed out it definitely needs brushing up.
My favorite parts:
-art was superb. Animation is very clean and visually appealing.
-music and sound effects are superb
-the concept is good, and it's relatively fast-paced... I actually thought maybe it could be even faster paced, considering half of the "offers" you pass up
Now what I didn't like:
-the premise of this game is "split-second decisions" yet I don't see how even optimal player strategy affects the outcome of the game. Because enemy attack power and health gradually increases it is important to upgrade both attack and defense. The "soul saves" must be purchased at fixed intervals and for practical purposes so must elixers (or armor to heal). As a result the progression actually felt linear, because even if I had a "choice" to upgrade attack or defense I would likely take the other the next time around, or simply not be able to afford it. So really the "choice," while it was technically there, was in reality very constrained.
-This, coupled with the randomness, made me put it down after three runs. My decisions as a player have really no tangible effect on my success if I'm doomed to a run where a dragon just shows up and kicks my ass (and it's impossible to just "hold on to a divine sword" because then you can't heal).
My suggestion would be to add more player options. You could also make the battles "timing" based ala Super Mario RPG where attacks do more damage or you block some damage if you click at the right time. This in my view would make it a lot more interactive rather than basically just an animation of my character eventually dying.