I apologise pre-emptively for how awful it looks
Animating characters can be complicated and requires practice, but also some prior studies.
If you have not done the basic animation tests such as the Bouncing Ball, and Flour Sack, I highly encourage you to do so.
Be careful of drawing animations in a literal descriptive way.
Each part feels as if it moves independently rather than coming together to create a cohesive piece of functional art.
You're being very timid with the pixels, keeping things looking the same through out the animation.
While that can help to save time, and I use the same concept quite often, there are ways to better balance unique and static parts of a frame.
For me it helps to do the same animation 5 to 8 times.
Here's my first vartiation:
Many parts of it could be improved, but I would most likely stop at this point, save it to branched filename, and then start over.
The next time I would do it differently.
It would still be a sword swing, but I would start from the first frame, or completely from scratch.
Then compare them all, figure out what works, what doesn't.
Maybe combine a few ideas or just choose the best one and then finish it off.
Also realize that its all a choice.
Everything I've said can be done the complete opposite way and yield a valid result.
In the correct context with intention, your animation could work fine.
As Alcopopstar mentioned, the motion is sort of undead like.