en_tn/col/02/15.md

made a public spectacle of them

In Roman times, it was common practice for the Roman armies to have a victory parade when they returned home, displaying all the prisoners they had captured and goods they had obtained. God was victorious over the evil powers and authorities. (See: rc://en/ta/man/jit/figs-metaphor)

by the cross

Here "the cross" stands for Christ's death on the cross. (See: rc://en/ta/man/jit/figs-metonymy)