Above all, (Επι πασιν, over all the rest of the armor), taking the shield of faith - In the word θυρεος, thureos, the apostle alludes to the great oblong shield, or scutum, which covers the whole body. See its description before. And as faith is the grace by which all others are preserved and rendered active, so it is properly represented here under the notion of a shield, by which the whole body is covered and protected. Faith, in this place, must mean that evidence of things unseen which every genuine believer has, that God, for Christ's sake, has blotted out his sins, and by which he is enabled to call God his Father, and feel him to be his portion. It is such an appropriating faith as this which can quench any dart of the devil.

The fiery darts of the wicked - Βελος, a dart, signifies any kind of missile weapon; every thing that is projected to a distance by the hand, as a javelin, or short spear; or by a bow, as an arrow; or a stone by a sling.

The fiery darts - Τα βελη τα πεπυρωμενα. It is probable that the apostle alludes to the darts called falarica, which were headed with lead, in or about which some combustible stuff was placed that took fire in the passage of the arrow through the air, and often burnt up the enemy's engines, ships, etc.; they were calculated also to stick in the shields and set them on fire. Some think that poisoned arrows may be intended, which are called fiery from the burning heat produced in the bodies of those who were wounded by them. To quench or extinguish such fiery darts the shields were ordinarily covered with metal on the outside, and thus the fire was prevented from catching hold of the shield. When they stuck on a shield of another kind and set it on fire, the soldier was obliged to cast it away, and thus became defenceless.

The fiery darts of the wicked, του πονηρου, or devil, are evil thoughts, and strong injections, as they are termed, which in the unregenerate inflame the passions, and excite the soul to acts of transgression. While the faith is strong in Christ it acts as a shield to quench these. He who walks so as to feel the witness of God's Spirit that he is his child, has all evil thoughts in abhorrence; and, though they pass through his mind, they never fix in his passions. They are caught on this shield, blunted, and extinguished.

the shield. The [thureos] was a large oblong shield, or scuta, like a door, [thura,] made of wood and covered with hides.

Genesis 15:1 After these things the word of the LORD came to Abram in a vision, saying, Fear not, Abram: I am your shield...

Psalm 56:3,4,10,11 What time I am afraid, I will trust in you...

Proverbs 18:10 The name of the LORD is a strong tower: the righteous runs into it, and is safe.

2 Corinthians 1:24 Not for that we have dominion over your faith, but are helpers of your joy: for by faith you stand.

2 Corinthians 4:16-18 For which cause we faint not; but though our outward man perish, yet the inward man is renewed day by day...

Hebrews 6:17,18 Wherein God, willing more abundantly to show to the heirs of promise the immutability of his counsel, confirmed it by an oath...

Hebrews 11:24-34 By faith Moses, when he was come to years, refused to be called the son of Pharaoh's daughter...

1 Peter 5:8,9 Be sober, be vigilant; because your adversary the devil, as a roaring lion, walks about, seeking whom he may devour...

1 John 5:4,5 For whatever is born of God overcomes the world: and this is the victory that overcomes the world, even our faith...

to quench.

1 Thessalonians 5:19 Quench not the Spirit.

The Panoply of God
'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.'--Eph. vi. 13. The military metaphor of which this verse is the beginning was obviously deeply imprinted on Paul's mind. It is found in a comparatively incomplete form in his earliest epistle, the first to the Thessalonians, in which the children of the day are exhorted to put on the breastplate of faith and love, and for a helmet the hope of salvation. It reappears, in a slightly …
Alexander Maclaren—Expositions of Holy Scripture Ephesians, Peter,John

The Wide Range of God's Grace
'Grace be with all them that love our Lord Jesus Christ in sincerity.'--Eph. vi. 24. In turning to the great words which I have read as a text, I ask you to mark their width and their simplicity. They are wide; they follow a very comprehensive benediction, with which, so to speak, they are concentric. But they sweep a wider circle. The former verse says, 'Peace be to the brethren.' But beyond the brethren in these Asiatic churches (as a kind of circular letter to whom this epistle was probably sent) …
Alexander Maclaren—Expositions of Holy Scripture Ephesians, Peter,John

The Sword of the Spirit
Difficulties meet us even in standing our ground; for the apostle, two or three times, bids us--"Stand." In the rush of the fight, men are apt to be carried off their legs. If they can keep their footing, they will be victorious; but if they are borne down by the rush of their adversaries, everything is lost. You are to put on the heavenly armor in order that you may stand; and you will need it to maintain the position in which your Captain has placed you. If even to stand requires all this care, …
Charles Haddon Spurgeon—Spurgeon's Sermons Volume 37: 1891