1. The trees and branches are very distracting because they have an odd shape and they're really dark. The cosplayer kinda blends into the background because her costume is dark, and the trees are dark.
2. This might've looked nice if the photo were in color, and we could see the face though. The silhouette's left hand blends into the clouds.
3. I like the pose, but I think the photo should be brighter.
4. I like the leading line of the sword, and the angle, but her face is too dark. Maybe use a reflector?
5. His dark suit blends into the dark trees well, so he doesn't stand out much. Maybe he'd stand out more if this were in color. The bright space between his hands look weird (photoshop error?). I think you should've blurred the background more