15 Brothers, to take from a human analogy, I say: even if it is a human covenant that has been ratified, nevertheless, no one can annul it or can add to it. Galatians 3:15
In the Greek OT (LXX), κύριος is the main word that replaces Yahweh (God’s name) from the Hebrew. This was done in the LXX because the Jews were afraid that they would take God’s name in vain (or blaspheme), thus breaking the law of Moses.
I would have to say that κύριος is a fitting title for God. If the verb means to ratify, to validate, to make legally binding, then κύριος is the one who ratifies, validates and make something legally binding. By example, God spoke the creation into existence. By speaking it, he ratified it, thus making it happen, thus putting it into existence.
This very idea could have been in John’s thoughts when he penned “In the beginning, there was the word/message”. When the word is spoken by the one who makes it legally binding, it comes into existence. The message about Jesus is the message that redeems all humans from their sin by putting their faith in him. When he speaks it, we are truly pronounced righteous before him and thus sealed with his empowering Holy Spirit.