Make it longer. I can't really give you any advice unless I can actually see some more work done with doing something other than an arm swing.
The pose is too choppy, I mean that by saying that the back-foot moves back for absolutely no reason. If anything, it would move back after the swing to emphasize some sort of power, but it isn't necessary. Two more things: the arm moves too slowly to convince me that it's a swing meant to harm someone, and if this were a real fight, he would have been shanked and raped violently for having such a strange pose and buildup. Weapon handling is much more than swinging an object. I would suggest looking up some sword-handling videos to boot, and look at how other animators integrate their animation style and real-life motions to give it a clean feel.
(It seems like you're just copying the previous frame and making adjustments like free transform and rotating every so often. It makes it look chopped up.)