I'm going to give my own review in case anything was missed in the comments.
Personally I thought the animation wasn't too great. It felt fluid for the most part, but an animation is more than a bunch of pictures sliding around. So here goes nothing.
1. The animation and the quality of the images provided.
-When you watch the animation the first time you can tell that the body seems a little off on either of the characters. Either they have giant chests, or their proportions are pretty off. My first experience in this animation is the arms. Although your art style may use this form, the overall professionalism about it lacks the human figure. It seemed to me that you were trying to form the anatomy well so that you could get a sense of realism with it. (Also the arm seems to get smaller when he throws the shuriken)
-The color scheme was well done. You managed to keep the viewer (me), not focused on the background but at the same time, when I noticed it, it was a nice image of the situation. Two dark warriors fighting in a battle to the death in a forest filled with fog, trees that seemed to have decayed after years of fighting death, and yet the amount of unseen life that has hidden in the forest.
2. The Music, Sound and Voice quality
-The music was definitely one of the best parts of the animation. The way it was presented to sit the situation was well done. There could have been better music choices, but for what you chose you still did a good job.
-The sounds and different effects in the animation were okay. When you hear them originally they sound good and work well with the animation. After a bit they become distorted and underwhelming. Your sounds definitely could be presented better if you used distance to determine the overall volume of the sounds.
-The voices. Eww is all I can describe this as. Your mic is either pretty junk or the editing behind the scenes made it hard to listen to. It sounds extremely muffled and veryyy scratchy. It hurt my ears and is probably the main reason you aren't getting a high score from most viewers.
Either way I enjoyed your effort at making a fighting scene and overall you could have done better. If I were you I would take the time to follow some tutorials to practice your anatomy so the next animation looks better than ever! I would also either see about getting a new mic, not using voice, or asking some voice actors to record different pieces for you to use for your animation.
Have a good day! 7/10