He hath made my mouth like a sharp sword. The author of the Epistle to the Hebrews says that "the Word of God" generally "is … sharper than any two-edged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow" (Hebrews 4:12).
Christian experience testifies that tiffs keen, searching, cutting power attaches in an especial way to the sayings of Jesus, which pierce the heart as no other words can do, and rankle in the soul, which is quite unable to forget them.
The imagery recurs in the Revelation of St. John (John 1:16; John 2:12, John 2:16; John 19:15, John 19:21). In the shadow of his hand hath he hid me. Either keeping him safe from the malice of his enemies, or reserving him until, "in the fulness of time," it would be fitting to reveal him to the world.
And made me a polished shaft, A weapon even keener than a sword, smoothed and polished, so as to make it pierce the deeper, and kept hid in God's quiver until the time came when it could be launched with most effect against the hearts of ungodly men.