He has made My mouth like a sharp sword, In the shadow of His hand He has concealed Me; And He has also made Me a select arrow, He has hidden Me in His quiver. (Isaiah 49:2)

• my mouth like a sharp sword. The Lord has given power to his Servant to speak effectively and thereby to conquer his enemies. His word is always effective (Isa. 55:11; Eph. 6:17; Heb. 4:12) 
• hid me. Messiah, before his appearing, was hidden with God, ready to be drawn out at the precise moment. (John MacArthur)

God had fitted and qualified him for the service to which he designed him. He made his mouth like a sharp sword, and made him like a polished shaft, or a bright arrow, furnished him with every thing necessary to fight God’s battles against the powers of darkness, to conquer Satan, and bring back God’s revolted subjects to their allegiance, by his word: that is the two-edged sword which comes out of his mouth. The convictions of the word are the arrows that shall be sharp in the hearts of sinners. (Matthew Henry)