"Blacking Compound" = candle soot When inletting ferrules, nose caps etc on a smokepole, you hold the object to be inlaid over a candle, then carefully wipe the edges - if you have a nice snug fit at the sides they will fool you into carving out the outline too much. Press the object in place firmly or lightly tap with a nonmarring mallet. Remove the inlay and carve away the black part. Repeat. Again and again....
For an irregular object like an arrowhead it is a pretty daunting task. Go slow, and I would really be careful with that Dremel!!! I use hand tools - micro carving tools, curved detailing rasps and the like. Don't trust myself on a finished bow with power tools!!!