Here "child" is a term of great love and approval. It is also likely that Timothy was converted to Christ by Paul, and so this is why Paul considered him like his own child. AT: "who is like my child" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# be strengthened in the grace that is in Christ Jesus
Paul speaks about the motivation and determination that God's grace allows believers to have. AT: "let God use the grace he gave you through your relationship to Christ Jesus to make you strong" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# among many witnesses
"with many witnesses there to agree that what I said is true"
# entrust them to faithful people
Paul speaks of his instructions to Timothy as if they were objects that Timothy could give to other people and trust them to use correctly. AT: "commit them" or "teach them" (See: [[rc://en/ta/man/translate/figs-metaphor]])