This verse in Proverbs is given as a second statement about rulers - and it comes from a positive point of view. Verse 14 dealt with the fury of a king - while this one deals with his favor.
The light of a king's face is life. No one knew this more than Esther, who dared come into the presence of king Ahasuerus without being summoned. She knew that there was a punishment for this kind of action - death. Only if he extended the golden scepter to her would she be delivered from the death penalty for such an offense. To receive such an action was to be allowed to see the king's face. That meant that he was showing her grace and favor.
The favor of the king is also compared to a cloud with the spring rain. This was called the "latter" rain - and it was the rain that was absolutely necessary if a good crop was to be expected. Without these latter rains, the crops would be killed by the lack of rain. When these clouds would come up over the land, people would rejoice because they knew that God had blessed them and that they were going to have a crop that would bear abundantly. So also the favor of the king meant that blessing was coming. In the culture at the time the king had absolute power. If he decreed that you were to die - you would die. If you knew his favor - then great blessing would come to you and your family.
We sing a song in worship at Calvary that goes this way, "Thou, O Lord, art a shield about me, Your my glory, and the lifter of my head." This song deals with something very similar to this verse. The lifting of the head was a symbol that the one who had previously bowed to the king was being allowed to see his face - and thus receive his favor. If you remember in the book of Esther, when the king was furious with Haman, a black bag was put over his head. This symbolized that he would NEVER see the face of the king again. It also meant death.
The amazing thing about this whole idea of the light of the king's face is the way that is reflects to us the message of the gospel. There is a King that we all have to approach one day at the end of the age. He is a King Whose holiness prevents us from coming before Him without being judged for our sin. Were we to try to approach Him unworthily, we would be consumed by His wrath and righteous judgment upon sin. But there is also One who has gone before us - Jesus Christ - and who has taken our sin and paid the full penalty for our sin. He has taken the judgment. Not only this, but He has also given us His perfect righteousness - by which we can stand before God accepted and welcomed. Truly Jesus Christ is the light of the King's face to us - and he is the reason God's favor can be granted to us. May God ever remind us of the grace gloriously showered upon us by His gracious act in Christ - and may we rejoice in His favor like the clouds filled with the latter rains. Christ has opened the way and brought us to see the King's face with favor - favor purchased by His death, burial, and resurrection. Glory to God for His grace, favor, and the joy of seeing His face in Christ Jesus.