Perhaps these clerics were imitating the example of Saint Paul in Ephesians 6:13-16, to wit:

"Therefore take the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand. Stand therefore, having girded your loins with truth, and having put on the breastplate of righteousness,
and having shod your feet with the equipment of the gospel of peace; besides all these, taking the shield of faith, with which you can quench all the flaming darts of the evil one. And take the helmet of salvation, and the sword of the Spirit, which is the word of God."