About 30 years ago, I was reading through a Passover Haggadah and was struck by a statement to the effect that God Himself had come down to save Israel from Egypt. "That's odd," I thought, "wasn't it an angel that struck the firstborn?"
I have searched the scriptures for many years, and have been unable to find a mention of this angel. Scripture is consistent on this point: it was God who struck the firstborn, it was God who passed over the houses when He saw blood.
There might have been angelic involvement in the Passover, but scripture doesn't mention it.
The closest I can find to such an angel in Exodus is Exodus 12:23. KJV and JND both mention a "destroyer" in that verse. Other translations I have checked render "destroyer" as "plague". Numbers 20:16 might be more promising.
A friend of mine points to Psalm 78:49, which I find unconvincing. In context, Psalm 78:44–50 is a pretty clear reference to the first nine plagues on Egypt, Psalm 78:51 brings in the tenth. Verse 49 appears as a summary of the first nine plagues. You could argue angelic involvement in the first nine plagues, based on Psalm 78, but not the tenth.
On the other hand, scripture refers to the tenth plague in terms of God's direct action, without an intermediate. Exodus 11:4ff and Exodus 12:12ff both make the claim that God would go through Egypt, judging it. That is unique to the tenth plague: in the first nine plagues, God in heaven acted against Pharaoh on earth. Only in the tenth plague does God claim He will come down. In the tenth plague – and only the tenth – God's presence in Egypt is promised.
This isn't some obscure point of minutiae. While I admit this is a subtle point, it is significant. God doesn't entrust the redemption of His people to angels. He takes direct action.
Notice that while Scripture is silent on angelic involvement in the Passover, there are certainly "destroying angels" in Scripture. 2 Samuel 24:15ff, 2 Kings 6:15ff, Psalm 78:49, and Revelation 9:11 are just a few examples. I have no doubt such angels exist. The point isn't that such angels don't exist, the point is that Exodus makes the express claim that God acted directly in the Passover, and makes no mention of those "destroying angels."
Psalm 8:3 describes the heavens as the work of God's fingers. Pharaoh's magicians described the plague of gnats as "the finger of God" (Exodus 8:19). God describes His redemption of Israel from Egypt as requiring His out-stretched arm (Exodus 6:6, Exodus 15:16). There is a progression here: creating the heavens took only God's fingers. But He used His out-stretched arm to redeem His people from slavery.
Do we appreciate how important God makes redemption? Do we appreciate that He put more effort into redeeming Israel than He put into making the heavens?
Do we appreciate that our full and final redemption from sin cost Him even more? Do we appreciate that the Son of God "bore our sins in His body on the tree?" (1 Peter 2:24).
God, who spoke the world into existence, suffered the pain and loss of giving His Son for us. This ought to touch our hearts.