Vincent's NT Word Studies
14. In part (apo merouv). Referring to the partial understanding of his character and motives by the Corinthians.15 Before (proteron). Rather, first of all. Instead of going first to the Macedonians, as he afterward decided. See 1 Cor. xvi. 5.
Second benefit (deuteran carin). Benefit is, literally, grace. Not a mere pleasurable experience through Paul's visit, but a divine bestowal of grace. Compare Rom. i. 11. Second refers to his original plan to visit Corinth twice, on his way to Macedonia and on his return.
Robertson's NT Word Studies
1:14 {As also ye did acknowledge us in part} (kaqws kai epegnwte hemas apo merous). Gracious acknowledgment (second aorist active indicative of epignwskw) to the original Pauline party (#1Co 1:12; 3:4) that he had seemed to care so little for them. And now in his hour of victory he shows that, if he is their ground of glorying, they are his also (cf. #1Th 2:19f.; Php 2:16).