Like much of Isaiah the verse looks both backward and forward. God gave the law on Mount Sinai; he was King of Israel; he saved them from Pharaoh and slavery in the Exodus and continued to save them from their enemies. Looking forward from Isaiah, Jesus gave a fuller interpretation of the law (Matthew 5); he is King of Kings and will return to judge; he saved us from slavery to our sins.
For reflection: Let us, again, use the verse from Isaiah as a starting point of praise to our God.
Let us pray. O Lord, you are our just judge and righteous lawgiver, you are our King, you are the one who saves us.