First off, I love the warm colours you've used here. Really works with the simplistic objects.
As for crits, what struck me is that I found the character sprite to be messy. After a bit of searching, I am guessing that there are two things that give me that impression.
First, it's the sparks. The black grain in the middle and jagged animation seems to drag down what could be an even better impression of a well executed walkcycle.
Second, the speedlines in the cutting animation. As there's a limit to how much you can AA lines that end in transparency, it looks pretty jagged compared to the character sprite.
I did some tests to see if I could fix it:

yours - mine - mine.
For the sparks, I used only "clean" angles that need no AA. I found that it could also look interesting having the sparks further back than dead on.
On the cutting, I usually find it better to use a full shape, stretching the colours and lines from the furthest point in the animation. (something Capcom uses a lot.) The first has emphasis on the metal, while the other on the blade. It can also be narrowed down, but I didn't feel like making a horde of edits.

I feel a solid shape (just shown for that one frame of course) would unify it with the style on the Bearmonbit... bonit... Hero character.
And just to add to what the other's been saying. Great idea on the clouds.
