Adam Clarke on Colossians 2:15

And having spoiled principalities and powers - Here is an allusion to the treatment of enemies when conquered: they are spoiled of their armor, so much the word απεκδυειν implies; and they are exhibited with contumely and reproach to the populace, especially when the victor has the honor of a triumph; to the former of which there is an allusion in the words εδειγματισεν εν παρῥησιᾳ, making a public exhibition of them; and to the latter in the words θριαμβευσας αυτους, triumphing over them. And the principalities and powers refer to the emperors, kings, and generals taken in battle, and reserved to grace the victor's triumph. It is very likely that by the αρχας και εξουσιας, principalities and powers, over whom Christ triumphed, the apostle means the נשיאות nesioth and רשות roshoth, who were the rulers and chiefs in the Sanhedrin and synagogues, and who had great authority among the people, both in making constitutions and explaining traditions. The propagation of Christianity in Judea quite destroyed their spiritual power and domination; just as the propagation of Protestantism, which was Christianity revived, destroyed, wherever it appeared, the false doctrine and domination of the pope of Rome.

In it - The words εν αυτῳ refer rather to Christ, than to the cross, if indeed they be genuine; of which there is much reason to doubt, as the versions and fathers differ so greatly in quoting them. Griesbach has left them out of the text.