The term USE A STROP ON is referring to the process of sharpening a blade. The two crossword solutions, WHET and HONE, refer to two different steps in the sharpening process. Whetting is the first step, which involves using a whetstone or other abrasive material to grind away metal from the blade and create a sharp edge. Honing is the second step, which involves using a strop to refine the edge and remove any burrs or imperfections.