Despite what people might tell you chemically sharpened points can be touched up with a file. The trick is knowing how to do it. Don't go mad. Light strokes going towards the point, working your way around the circumference of the point are what is required. I use the groove of the Eze Lap to start with, then the flat side to finish the job off. The groove is also useful for straightening a point that has turned over.
I described the hook sharpening process for lure trebles in an article on dlst.co.uk and it applies just the same for singles and with a diamond file. I'll repeat the important stuff here.
Always file towards the point of the hook. Never use a back-and-forth motion. File the sides of the point first (A &B), then the outside faces (C & D), and finally the faces on the inside of the hook where the barb is (E & F).
With curved points the inside is impossible to sharpen. So don't bother. Unless the point has been turned in it won't make any difference as sharpening the other 'faces' will suffice.