The Greek verbs used in verses 18-20 are appropriate in each case to the particular piece of military equipment mentioned. A breastplate is something you wear, a helmet is something you place on you, a “shield” is something you take up, and a “sword” is something you sharpen.

He will put on righteousness as a breastplate: Some versions (Revised English Bible, New American Bible) have “justice” instead of righteousness. The Greek noun here refers to “correct judgment.” It is parallel in meaning with justice in the next line; there justice translates a Greek noun often rendered “judgment.” The breastplate was the piece of armor that covered the soldier’s chest. Since Good News Translation did not use the word “armor” in verse 17, it uses it here. Contemporary English Version has “The Lord will protect his chest with deeds of fairness.”

And wear impartial justice as a helmet: God’s justice (or, “judgment”) is described as impartial, that is, fair to all concerned; Good News Translation translates “genuine.” Traduction œcuménique de la Bible has a different understanding of the word, and translates “judgment from which there is no appeal.” New American Bible seems to reflect this with “sure judgment,” and Revised English Bible with “inflexible judgement.” Any of these are acceptable. A possible model is “and for a helmet he will wear genuine [or, true] justice.”

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on The Wisdom of Solomon. (UBS Helps for Translators). New York: UBS, 2004. For this and other handbooks for translators see here.