John Chrysostom

"And being in readiness to avenge all disobedience, when your obedience shall be fulfilled." Here he alarmed these also, not those alone: 'for,' says he, 'we were waiting for you, that when by our exhortations and threatenings we have reformed you, and purged and separated you from their fellowship; then, when those only are left who are incurably diseased, we may visit with punishment, after we see that you have really separated from them. For even now indeed ye obey, but not perfectly. …

Homily 21 on 2 Corinthians ↗

Theophylact of Ohrid

Here he also frightens the Corinthians. We are waiting for you, he says, so that when you have been corrected by our instructions and have ceased your fellowship with the slanderers, we may subject to punishment only those who are incurably afflicted. Punishment is ready on our part, but since you have fellowship with them, we do not employ it for now, lest the blow strike you as well. With the words "when your obedience is fulfilled," he hints that although they are obedient even now, they are not yet perfectly so. …

Commentary on 2 Corinthians ↗

Thomas Aquinas

The third effect is the correction of sinners; as to this he says, being ready to punish every disobedience, i.e., having the readiness and free will to punish all disobedience: "And two-edged swords in their hands" (Ps. 149:6). This will occur when your obedience is complete, i.e., when you are perfectly obedient, because if you are willing to obey, there will be no reason for punishing the disobedience of others and your own. …

Commentary on 2 Corinthians ↗