Put ye on the armor of God, that ye may be able to stand against the deceits of the devil. For our wrestling is not against flesh and blood; but against principalities and powers, against the rulers of the world of this darkness, against the spirits of wickedness in the high places. Therefore take on the armor of God, that ye may be able to resist in the evil day, and to stand in all things perfect. Stand therefore, having your loins girt about with truth, and having on the breastplate of justice, And your feet shod with the preparation of the gospel of peace: In all things taking the shield of faith, wherewith you may be able to extinguish all the fiery darts of the most wicked one. And take unto you the helmet of salvation, and the sword of the Spirit.
The passage above, from The Epistle of St. Paul to the Ephesians, seems on the surface to be comparing, in metaphor, aspects of the Christian faith to the various pieces of armor a warrior might wear. Each item protecting or arming the faithful in the way that a breastplate or sword might. As metaphor, and as spiritual truth, it is powerful. However, it also speaks to a later tradition.
It speaks to the Lorica.