I found your composition a little harder to understand than it needs to be.
Here are a few things to perhaps consider.
The motion blur on the knife would be caused by a slower shutter speed on a camera. But if the knifes motion is blurred, then the motion of his whole arm would be blurred as well. And realistically he would be rotating his whole body to make that slice, and there would be a slight blur to that as well, no sharp edges.
Depth of field is created by a larger aperture on a camera, which is related to a fast shutter speed.
Essentially I found it strange that you have both depth of field and motion blur in your composition, it is highly uncommon in photographs.
Also remember that a painting does not have the same constraints as a camera, you can do whatever you want.
However I think that removing the motion blur and showing the strength and speed of his slice with gesture would be an improvement.
If you prefer to keep the motion blur, un-blurring the background (mostly), and blurring the foreground using motion, instead of focus, would be an improvement as well.
One last thing I want to point out is that while the blood and electricity look very nice. They have a lot of contrast and demand the attention of the eye. Try to keep interesting details for people to notice, but not steal attention from the whole image.
Overall I really enjoyed your piece. I only write this critique because I thought your work was intriguing and deserved the time of day.
