The monarch is supposed to be the defender of this faith using these spiritual weapons as hereby described.
Ephesians 6:10-20 King James Bible
Put on the whole armour of God, that ye may be able to stand against the wiles of the devil.
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
Wherefore take unto you the whole armour of God, that ye may be able to withstand in the evil day, and having done all, to stand.
Stand therefore, having your loins girt about with truth, and having on the breastplate of righteousness;
And your feet shod with the preparation of the gospel of peace;
Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked.
And take the helmet of salvation, and the sword of the Spirit, which is the word of God:
Praying always with all prayer and supplication in the Spirit, and watching thereunto with all perseverance and supplication for all saints;
And for me, that utterance may be given unto me, that I may open my mouth boldly, to make known the mystery of the gospel,
For which I am an ambassador in bonds: that therein I may speak boldly, as I ought to speak.
http://www.lectionarystudies.com/sunday21bae.html
i] The belt. As Christian soldiers prepared for battle, we are to put on truthfulness like a belt. In simple terms, tell the truth.
ii] The breastplate. We are to put on right behavior like a breastplate. Be Christ-like is the exhortation.
iii] Shoes. We are to put on peacefulness like shoes. The most popular interpretation is in terms of witnessing, evangelism. Yet, Paul possibly means something like speaking peace - being peaceful rather than argumentative.
iv] The shield. We are to take up trustworthiness like a shield. Again, this image is often interpreted in the terms of faith in Christ - saving faith. Yet, when treated as an ethical quality, the shield represents faithfulness rather than faith in God.
v] The helmet. We are to put on salvation like a helmet. This image is not an easy one. The most accepted view is to see the image in the terms of assurance - "be sure of your salvation." Yet, this is not really an ethical exhortation, but then there is no need to expect Paul to make all the pieces of armor ethical. To support this view Isaiah 59:17 describes God as wearing victory like a helmet.
vi] The sword. We are to take up prayer like a sword. The accepted interpretation is the taking up of the word of God, the Bible. So, the exhortation is that we read the Bible and believe in it. There is though a strong possibility that the exhortation is to prayer. The sword then represents praying in the Spirit. This view sees the prayer of faith through the Spirit as prayer according to the will of God (prayer that is based on His promises).