What does Luke 22:43 mean?

Luke 22:43–44 is not found in the oldest manuscripts. Nor is the content repeated in the other Gospels. However, it doesn't demand any unique theology. Jesus is on the ground in the garden of Gethsemane, praying that God the Father might choose a different way to save the world (Luke 22:42; John 3:16). It appears the Father has sent His answer. The angel strengthens Him. Then Jesus prays "more earnestly; and his sweat [becomes] like great drops of blood falling down to the ground" (Luke 22:44).

Scholars debate as to how an angel could "strengthen" God the Son. Jesus has just expressed his human nature's desire that He not suffer this terrible experience. His divine nature is ready to follow the Father's instructions wherever they may lead. It seems the angel is confirming that the original plan stands. The angel is strengthening Jesus' commission but also supporting Him as He mourns what is to come.

This is a bit different than the last time angels ministered to Jesus. That was at the end of forty days of fasting and three temptations by Satan (Matthew 4:11). In one of those temptations (Matthew 4:6), Satan quoted Psalm 91:11–13:

For he will command his angels concerning you
to guard you in all your ways.
On their hands they will bear you up,
lest you strike your foot against a stone.
You will tread on the lion and the adder;
the young lion and the serpent you will trample underfoot.

It's interesting to compare these verses to what is happening here. Later, Peter will refer to Jesus as "a stone of stumbling, and a rock of offense" (1 Peter 2:8). Jesus avoids tripping on the desire to avoid the cross. As a result, He dies and rises again, trampling the "roaring lion, seeking someone to devour" (1 Peter 5:8) and crushing the head of Satan, the serpent in the garden (Genesis 3:15).