Paul speaks of chains when he means his imprisonment. AT: "Remember me and pray for me while I am in prison" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here "grace" stands for God, who shows grace or acts kindly to believers. AT: "I pray that our Lord Jesus Christ would continue to act graciously toward you all" (See: [[rc://en/ta/man/translate/figs-metonymy]])