For we rejoice (chairomen gar). Paul had far rather be weak in the sense of failing to exercise his apostolic power because they did the noble thing. He is no Jonah who lamented when Ninevah repented.
Your perfecting (humōn katartisin). Late word from katartizō, to fit, to equip (see verb in 2Co 13:11). In Plutarch, only here in N.T.