causeth us to triumph = leadeth us in triumph (Greek. thriamheud), or triumphs over us as in Col_2:15. Only in these two places. Paul was a captive won by grace. In a Roman triumph there were captives destined to be spared and captives destined to death. See 2Co_2:16.
by = by means of. Greek. dia. App-104. 2Co_2:1. Paul gave evidence of the wisdom which dwelt in Him (Col_2:3) in his own conversion (1Ti_1:16), as well as in his preaching.