A.T. Robertson Commentary 2 Corinthians 11:6

"But though [I be] rude in speech, yet [am I] not in knowledge; nay, in every way have we made [this] manifest unto you in all things." — 2 Corinthians 11:6 (ASV)

Rude in speech (ιδιωτης τω λογω). Locative case with ιδιωτης for which word see on Ac 4:13; 1 Corinthians 14:16,23,24. The Greeks regarded a man as ιδιωτης who just attended to his own affairs (τα ιδια) and took no part in public life. Paul admits that he is not a professional orator (cf. 10:10), but denies that he is unskilled in knowledge (αλλ' ου τη γνωσε).

Among all men (εν πασιν). He has made his mastery of the things of Christ plain among all men. He knew his subject.