Comment by WillAdams

Find a chunk of raw metal (possibly meteoric iron, more likely copper) of a suitable size/shape, find a tree, using a sharp rock, saw off a suitable branch, split it open, insert the metal chunk, using vines or the intestines of a small animal secure it in place --- if desired, allow the tree to grow around the inclusion for a couple of years, then use a sharp rock to saw off the branch at a suitable length.