This question is based on the assumption that the "Angel" in Gen 48:16 is distinct from God. Note that this "Angel" is the one who redeems Jacob from all evil. Observe what other Scriptures say about the redeemer:
- Isa 49:26 - ... Then all mankind will know that I, the LORD, am your Savior and your Redeemer, the Mighty One of Jacob.
- Isa 44:6 - Thus says the LORD, the King and Redeemer of Israel, the LORD of Hosts: “I am the first and I am the last, and there is no God but Me.
- Isa 44:24 - Thus says the LORD, your Redeemer who formed you from the womb: “I am the LORD, who has made all things, who alone stretched out the heavens, who by Myself spread out the earth
Thus, YHWH claims to be Israel's (Jacob's) Redeemer who, in Gen 48:16 is equated with the "Angel". This common in the OT where YHWH calls Himself and angel/messenger - see Gen 16:7-13, 22:11-17, 32:24-30, 48:16, Ex 3:2-6, 32:34, Num 22:22-35, Josh 5:13-15, Judg 2:1-4, 6:11-23, 13:3-23, Isa 63:9, Dan 3:25, 28, Hos 12:4, 5, Zech 3:1-7, Mal 3:1.
Sometimes, YHWH calls Himself "The Angel of God" as per, Gen 6:13, 8:15, 9:8, 17, 15:13, 17:3, 4, 21:12, 16-21, 35:1, 10, Ex 4:3-8, 6:2, 23:20, 21, Deut 1:6, 1 Kings 12:22.
In Isa 63:9, “the Angel of His [LORD’s] presence saved them”, and is almost certainly a reference to the same being. The same is true of Ex 23:20, 21.
In other places we see that the LORD sends the LORD:
- Zech 2:6-12 – the LORD (= YHWH) claims three times that He has been sent by the LORD.
- Isa 48:11-16 – again, the LORD has been sent by the LORD.
Thus, unsurprisingly, Jesus is the messenger to the human race and underlines the importance that the Godhead places upon such messages.
Either way, we have a typical poetic parallel between:
- The God who has fed me all my life long to this day
- The Angel who has redeemed me from all evil
Thus, Jacob asks YHWH to bless Joseph.
Benson arrives at the same conclusion:
Genesis 48:16. The Angel which redeemed me — Not a created angel
surely, but Christ, termed an angel, Exodus 23:20, and the Angel of
the covenant, Malachi 3:1, and who was the conductor of Israel in the
wilderness, 1 Corinthians 10:4-9. Add to this, that this Angel is
called Jacob’s Redeemer, a title appropriated by God to himself,
Isaiah 43:14; Isaiah 47:4; is said to redeem him from all evil, and
therefore from sin, from which certainly no created angel, but only
Christ can deliver us, Matthew 1:21; and he is worshipped and prayed
to by Jacob here, for the blessing desired for Joseph’s sons: all
which circumstances show, that he was God and not a creature. From all
evil — A great deal of trouble and hardship he had had in his time,
but God had graciously kept him from the evil of his troubles. It
becomes the servants of God, when they are old and dying, to witness
for God that they have found him gracious.
Gill says something very similar:
The Angel; not surely a created angel, but Christ Jesus, who is called
an Angel, Exodus 23:20, and the Angel of the covenant, Malachi 3:1,
who was the conductor of the Israelites in the wilderness, as plainly
appears by comparing of Exodus 23:20,21, with 1 Corinthians 10:4,9.
Add hereunto, that this Angel is called Jacob’s Redeemer, which is the
title appropriated by God to himself, Isaiah 43:14 47:4, and that from
all evil, and therefore from sin, from which no created angel can
deliver us, but Christ only, Matthew 1:21; and that Jacob worshippeth
and prayeth to this Angel no less than to God for the blessing, and
that without any note of distinction, the word bless being in the
singular number, and equally relating to God and to the Angel; and
that the Angel to whom he here ascribes his deliverances from all
evil, must in all reason be the same to whom he prayed for these very
deliverances which he here commemorates, and that was no other than
the very God of Abraham, as is evident from Genesis 28:15,20,21