Albert Barnes Commentary Zechariah 2:9

"For, behold, I will shake my hand over them, and they shall be a spoil to those that served them; and ye shall know that Jehovah of hosts hath sent me." — Zechariah 2:9 (ASV)

For behold I will shake My hand against them – As God promised long ago against the enemies of His people, and they will be spoils to those who served them habitually.

And you will know that the Lord of hosts has sent Me – Theodoret:

“He was sent, not as God, but as Man. For as God He is equal to the Father. For He says, I am in the Father and the Father in Me, and, The Father who dwelleth in Me He doeth the works (John 14:10), and, I and My Father are one (John 10:30), and He who hath seen Me hath seen the Father (John 14:9). But He is sent, as Man, fulfilling the dispensation for us, not lessening the divine nature. The prophet then intimated not the duality only, but the equality of the persons.”