In these last few chapters Paul defends his ministry. He defends his ministry here in 10 on general terms, in 11against the "false" apostles and on his ministry experience and, finally, in 12 based on his spiritual experiences. Paul faced many difficulties in planting churches and building spiritually mature leaders to be overseers at them.
Here in 10 Paul is putting up a defense against nameless accusers and detractors. Apparently he has been accused of being forceful in writing but somewhat wimpy in person (10). He has been accused of "overstepping his limits (14)." He responds to his detractors by noting that they are making the wrong comparison (only comparing themselves to themselves) and that they are building their boastfulness on "someone else's sphere of action (16)."
Of particular note are verses 4-6. Paul is describing our weapons. There is 1) divine power to destroy strongholds (4); we destroy arguments against the knowledge of God (5); and to take every thought captive (5). The first is the divine power of God the others on this list are borne of discipline. We study and we learn to refute the false arguments against the faith and we discipline our minds by learning to take every thought captive. These abilities and tools are not routine or random but are born of a long season of prayer and living a disciplined spiritual life.