To stop a bleeding wing feather (called blood feathers), the feather needs to be completely removed. With the wing fully extended, grasp the quill of the feather as high as possible above the crack with forceps or a tweezers. Since the feather is attached to the covering of the wing bone, firmly grasp the bone of the wing and gently pull the feather out of the follicle. If some hemorrhage occurs, apply pressure to the follicle. Do not use clotting powders in the feather follicles.
For more information, please read Bleeding Feathers.