Many in Israel had to be terrified during this time. God had declared frightening prophecies of judgment. Assyria would come and serve as the rod of God to discipline them. How would you feel - even if you were among the remnant that had not bowed the knee to Baal? Personally, I'd probably be scared to death!
In this passage we see that God takes notice of our frailties by the very fact that he is rousing those who by grace are standing strong to help others do the same.
"God's prophets and ministers are charged to comfort those who could not yet recover from the fright they had been put into by the Assyrian army with an assurance that God would now return in mercy to them. This is the design of the gospel - to strengthen those that are weak and to confirm them. Among true Christians there are many who have weak hands and feeble knees and it is our duty not only to bear with the weak but to do what we can to confirm them." (Matthew Henry)
The New Testament bears the same testimony and call. "Now we who are strong ought to bear the weaknesses of those without strength...." (Rom 15:1). "And we urge you brethren, admonish the unruly, encourage the fainthearted, help the weak, be patient with all men" (1 Th 5:14).
God knows our frame. He knows our weaknesses. He knows that we are but dust. He cares, He strengthens us and he often uses the body of Christ - His church - as the arms that lift us up and carry us through the storms of life.
God was about to deal with Israel in Fatherly discipline. After that He would recompense the nations who would be His rod. There had to be much fear in the camp. Yet they needed to "take courage and fear not. Behold, your God will come with vengeance; the recompense of God will come, but He will save you."
The same is true today. Take courage my friends, God will right all wrongs. In the meantime may we be about the business of encouraging the exhausted among us.
In His glorious grace,