Jehovah’s Witnesses teach that Michael the arch-angel is Jesus. So did Michael swear the oath to Abraham at Genesis 22:15-17?

My point is why does Michael the arch-angel swear an oath on behalf of God and multiply Abraham's seed at Genesis 22:16-17 in light of what Hebrews 6:13-14 states? "For when God made the promise to Abraham, since He could swear by no one greater, He swore by Himself, verse 14, "saying, "I will surely bless you, and I will surely multiply you." So again, how can Michael swear an oath on behalf of God since no one is greater than God Himself? It's right there in Genesis 22:15,16, "Then the angel of the Lord called to Abraham a second time from heaven, and said, "By Myself I have sworn etc. How can this be "reconciled?" The Hebrew word for "angel" is "malak." This word means "messenger." The word can refer to an actual angel like Michael or it can refer to human "messengers," it all depends on the context. At Malachi 3:1, "Behold I am going to send my "malak/angel/messenger," and he will clear the way before Me, and the Lord whom you seek, will suddenly come to His temple; and the "malak/angel/messenger" of the covenant, in whom you delight, behold, He is coming," says the Lord of hosts." Mark 1:1-4 identifies John the Baptist as the angel/messenger who will clear the way of the Lord. By the way, the prophet "Malachi" is obviously a human prophet and his name is from the Hebrew word, "malak." I contend that the angel of the Lord is not an actual angel named Michael. The angel of the Lord is the pre-incarnate Jesus Christ. This is because God the Father has no separate manifestation from the Son. The Son is the only manifestation and revelation of the Father. To see the Son is to see the essence of the Father, John 1:1, 18; 10:30; 12;45; Colossians 1:15; Hebrews 1:3. Moreover, the angel of the Lord first appears as the angel of the Lord at Genesis 16:7-14, Genesis 22:11-15, Exodus 3:2-4, Numbers 22:22-38, Judges 2:1-3, Judges 6:11-23, Judges 13; 3-22, Zechariah 1:12 and at Zechariah 3:4. Since Jehovah Witnesses believe Michael is an actual angel, well, angels CANNOT SWEAR OATHS on behalf of God, especially since God Himself claims there is no one Greater than Him at Hebrews 6:13-14. And another thing, the following is what the Jehovah Witnesses said? Under the article "The Word" in the JW reference work Insight on the Scriptures Vol. II page 1203 it says this: "In a similar way God’s firstborn Son doubtless served as the Mouth, or Spokesman, for his Father, the great King of Eternity. He was God’s Word of communication for conveying information and instructions to the Creator’s other spirit and human sons. It is reasonable to think that prior to Jesus’ coming to earth, on many of the occasions when God communicated with humans he used the Word as his angelic mouthpiece." Citing a number of scriptural citations, the article assumes that Jesus was the angel that: stopped Abraham from sacrificing Isaac; spoke to Moses through the burning bush; may have been the angel that was charged with leading the nation of Israel through the wilderness. In all except the latter case, the scriptures referenced specifically mention "Jehovah's angel." So the Jehovah's Witnesses belief that Jesus appears in the OT is primarily based on Jesus identity as "The Word" as well as the OT wording "Jehovah's angel." It is true that Jesus Christ is the "Word/Logos" and Jehovah's angel/the angel of the Lord. The problem they have is twofold. They claim that the Word/Logos/Son is "a god." Even "a god" cannot swear an oath on behalf of "THE GOD." So if the JW's are right, who swore the oath, Michael,"a god" or both?