Before I get into the specifics of that particular passage though, I'd like to just say something about the "armor" that's mentioned there. Even though we've now got different and more exotic materials, the various pieces of "armor" are still pretty much the same. They still pretty much cover the same areas of the body and serve the same purpose.
The first piece we see is the "girdle or belt of truth." Think about what a "belt" does. It's what holds our clothing, our uniform if you will, together. Wouldn't you agree that "The Truth" is what clothes the Christian soldier? Next we see the "breastplate of righteousness." An item of "armor" that not only protects the upper torso area but, is right out front for everyone to see.
Then we see that our feet are "shod" with the "preparation of the gospel of peace." Could you imagine a soldier going into battle barefooted? In Paul's day the soldiers wore heavy metal shoes called "greaves" which protected their feet from traps and sharp sticks hidden to incapacitate them. And what are those devious things designed to do? To stop them from advancing. Can you not see how the knowledge of the "gospel of peace" works for us in similitude of the protective shoes of soldiers. By training (studying and knowing) the Gospel, The Truth, we'll not fall into a trap of error put out there by the army of Satan. We'll be protected and able to keep marching on.
We carry the "shield of faith." A piece of "armor" which we can hold out in front of us and it will protect us from the "fiery darts of the wicked." Paul says this piece of "armor" is to be taken "above all" which is just a way of saying that this is the "chief" piece or more necessary than the others. How so? Well, look at it this way: the others are fixed in place and protect a particular part of the body whereas the "shield" is movable. We can turn it towards whichever direction the "fiery darts" are coming from.
And also notice that with this item of "armor" we can "quench" those "fiery darts" which represent efforts by "the wicked" to inflict grievous wounds on us. Efforts that if allowed to penetrate our spiritual hearts could "kill the soul" (Mt. 10). But our "faith" will put out, or render ineffective, those attempts.
Then we put on our heads the "helmet of salvation." We all know what a helmet does, it protects the part of our body that directs the rest of the body. In the like manner that it "saves" the mortal body, it "saves" the immortal soul. We should always possess the "hope of salvation" in our minds which, in reality, is the ultimate goal of winning the battle against The Devil.
Have you noticed that all of these pieces of "armor" so far are things of a defensive nature? That all these various items are designed to protect us? Taking note of that brings us to the last piece of the "whole armor of God" - our only offensive weapon, the "sword of the Spirit."
Notice here that it is the "sword" of The Spirit (capital S). Simply stated, it's the weapon provided to the "soldiers of Christ" with which to inflict wounds to the enemy. That weapon, that "sword" is the "Word of God." (Heb. 4:12) It is what we use to refute false doctrine. To "convince the gainsayers." (Titus 1:9)
We have a great example of just how to wield it too. Just like Christ did in resisting Satan's temptations in the wilderness (Matt. 4) when He cited God's Word by saying "it is written." And please understand that it's not "our sword." We did not make it. It's given to us by the "Spirit of God." It's the "Word" that He delivered to us for the purpose of attacking the forces of evil.
In wrapping up our thoughts on the "armor of God" allow me to point out a couple more things to you about this ongoing warfare that the righteous are engaged in. There is another aspect we need to consider beyond just the physical preparations. Just as important in this fight is our mental preparedness.
I cited Eph. 6:11-17 as our passage of study, but I'd like you to notice verse 10 where we're told to "be strong in the Lord." Then in verses 11-17 we find the word "stand" or "withstand" used four times. What the use of those words means is that, even though we're wearing the "armor," we've got to be strong. Mentally strong. We've got to be courageous, to be stout-hearted. Or, as Paul said it in 1Cor. 16:13 "Watch ye, stand fast in the faith, quit you like men, be strong."
Brethren, let me close with this last thought. Christians are warriors. We are not appeasers when it comes to defending the Truth. There are no negotiated settlements between God's army and the forces of Satan. We "stand fast in the faith" and we wield our "sword," our "it is written" because we know, beyond a doubt, who the final victor is in this war.
David, the great king and psalmist, said these words in Psa. 144:1 and I think that all Christians should echo his words of praise. Read them with me and see if you don't agree. "Praise the Lord, who is my Rock. He trains my hands for war and gives my fingers skill for battle." (NLT)
Shouldn't we thank God for our warrior training? For both our defensive "armor," but especially our offensive weapon - His Word? I certainly think so.