The meaning only becomes clear when the element of faith is applied to what are metaphorical "instructions". The instructions do not speak of anything literal, but of spiritual elements that a Christian applies to a spiritual situation.
It is vital to know what preceded Paul's 'final' instructions to his readers. If we do not grasp what was stated first, we will never be able to do that which is final, because we won't understand it. So, here is a synopsis of what built up to Paul's final instructions, copied from the NIV Study Bible.
I. Greetings (1:1-2)
II. The Divine Purpose : the Glory and Headship of Christ (1:3-14)
III. Prayer that Christians may realise God's purpose and power (1:15-23)
IV. Steps towards the fulfilment of God's purpose (2:1-10)
V. Practical ways to fulfil God's purpose in the Church (4:1-6:20)
VI. Conclusion (6:21-24)
Your question involves section V., particularly 6:10-20, Strength in the Spiritual conflict. The Church Paul wrote to knew all about that spiritual conflict because they were in the thick of it. Their public stance for Christ as the only Lord and Saviour they would acknowledge brought the wrath of the Roman empire against them, as well as ridicule from Greeks, and hatred from Jews. Paul was showing them how to stand fast in their faith, unmoved.
If Christians are unaware of this spiritual battle of the world against Christ's Church, the verses in question will be lost on them. But those who are aware of spiritual realities at back of all that goes on in this material world, see the need to use what God has provided the Church with to stand fast for Christ. It takes faith to both see the reality of the spiritual battle we are in, and faith to 'pick up' the metaphorical 'equipment' God has given the Church.
Sadly, too many people in the Church think it's the job of their leaders to do whatever is needed to promote Christ in a largely Christless world. They think that if they just attend services of worship occasionally, that's all that's expected of them. Not so, according to that letter to Christians in Ephesus! We are to be engaged in a spiritual battle and, to not only stand fast in faith but to fight against spiritual forces in high places, to counteract the spirit of the air, the rulers of the darkness of this world, against spiritual wickedness.
"For the weapons of our warfare are not carnal" Paul said in 2 Corinthians 10:4. He adds that they have divine powers to demolish spiritual strongholds and all the pretensions that set themselves up against the knowledge of God. When we are equipped by God through his Holy Spirit, we have the faith and the ability to "take captive every thought to make it obedient to Christ, casting down vain imaginations. Spiritual eyes of understanding open up the whole matter, and it takes the faith of Christ for us to be able to see the real enemies, and the only spiritual form of combat that we can use, both to stand firm in our faith, and to counteract evil spiritual forces all around us.