Jamieson, Fausset and Brown on 2 Corinthians 13:9

9. are glad--Greek, "rejoice."

when we are weak--having no occasion for displaying our power; and so seeming "weak," as being compassed with "infirmities" (2Co 10:10; 11:29, 30).

ye ... strong--"mighty" in faith and the fruits of the Spirit.

and--not in the oldest manuscripts.

we wish--Greek, "pray for."

your perfection--literally, "perfect restoration"; literally, that of a dislocated limb. Compare 2Co 13:11, "Be perfect," the same Greek word; also in 1Co 1:10, "perfectly joined together"; Ep 4:12, "the perfecting of the saints."