Frank,
I being one who works with sharp tools, know that nothing can sharpen iron better than a sharpening stone.
Jesus is our rock, Our sharpening stone. Some try to strike against that stone (resist surrender), and the effect is a dull blade, while others allow that stone to hone our blade to fine edge (full surrender).
 
I pray this adds to the analogy, as in where two or three are gathered in his name, the "sharpening stone" will be there.....(Thoughtful pause)......Amen! Enjoyed your post.
 
Jesus Loves You....(That is for Gino, for making me feel guilty about closing with "God Bless")
 
David H