With a metal match a short length of hacksaw blade is perfect. They come ready drilled for a lanyard , are sufficiently hard and cheap. Your knife has been honed to a razor sharp edge for shaving fuzz sticks for tinder and defending yourself from the pair of big eyes just beyond the soon to be lit fire ( which usually turn out to be kangaroo rat <img src="images/graemlins/grin.gif" alt="" />.) Now why would you want to dull it shaving magnesium or striking a metal match? You could use the spine, provided it has a squared edge. Remember that many knifes are either zone or uniformly tempered. It needs to be relatively hard and free from the epoxy type finishes . The cotton acts as a wick, so either natural or poly will work. I like to soak mine in melted vaseline and then roll most of the jelly out, leaving a slighty greasyball that can be pulled apart and fluffed.