Kegan, Picture a broadhead that has been sharpened with a course stone...that kind of serration.
Instead of laying the file flat against the beveled edge of the broadhead, turn it 45degs so the corner of the file is on the edge. Drag the corner from the back of the blade to the point, in a quick motion. If you look close, you will see small grooves coming into the edge at 90deg. The edge will have a micro-serration. Lay the file flat and dress up both the front and back to remove the burr. Pat