"Sweat" is not a metaphor in that passage; it was literal perspiration.
Yes literal sweat to indicate he was working, sufferings unto death drinking the cup of wrath just like it informs us. . He was not just sweating because he was just standing there. Nothing about the temperature hot or humid?
Sweating bullets the cup of wrath.
Matthew 26:38 Then saith he unto them, My soul is exceeding sorrowful, even unto death: tarry ye here, and watch with me.
It would seem all things that can carry DNA are used to represent the unseen work of the Holy Spirit.
Spit is used in another metaphor used in parable in a similar way to represent the working of the Holy Spirit .
Giving ears to hear and a tongue to confess.
Mark 7:33 And he took him aside from the multitude, and put his fingers into his ears, and he spit, and touched his tongue;
Literal DNA the temporal things seen.
When we mix the unseen things of God with the temporal seen (DNA) of men. Then we can rejoice he has given us valuable tools to rightly divide the parables. He hides the understanding from those who only look to the literal historical .(corrupted)
2 Corinthians 4:18 While we look not at the things which are seen, but at the things which are not seen: for the things which are seen are temporal; but the things which are not seen are eternal.
But again mixing according to the prescription above reveals the mysteries of faith . There are no mysteries as understanding that come by walking by sight .Look and see to those who do mix faith. The understanding hid in the parable remains a mystery to those who do not divide the parable. .
For who has a living abiding hope for what they already see? No man has received the promised new bodies. No one is walking on water.