I am saddle stitching a large messenger bag and have three stitched together edges that need to be evened up with each other.....one layer is a stiff harness leather reinforcing strip and the other two are buffalo edges of my zipper gusset. Do I level them with a knife , glass, or by sanding? Very little clean up is needed and I would think a sanding block would give me the straightest edge but I have not understood leather sanding so far as I am a leather newbie.....I find that when I sand, I remove what I need but am left with the bigger problem of shaggy fibers. If sanding is the answer, what grit and type of sandpaper? and is sanding do-able with soft fleshy buffalo???? thanks!!!!