6 And hath made us kings and priests unto God and his Father; to him be glory and dominion for ever and ever. Amen.
[AD 990] Oecumenius on Revelation 1:5-6
The structure of these words goes from the end to the beginning. He means that it was to Him who hath loved us that glory and empire are owed.
For how did He not love "who gave Himself as a ransom"(1Tim. 2:6) on behalf of the life of the world.

And washed us from our sins in his own blood: For He Himself removed the handwriting of the decree that was against us, which was contrary to us. And he hath taken the same out of the way, fastening it to the 'wood of His' cross, (Col. 2:14) paying for our sins by His own death, and with His own blood he freed us from the error of our transgressions. He did this by becoming obedient unto death, even to the death of the cross, (Phil. 2:8) and so healing our disobedience.

And hath made us a kingdom: And what does it profit of our becoming, as he says, priests to God and his prophets? That man should be thought worthy of these things proves to us the kingdom to come and the assurance of the unspeakable glory in the present. For this is even greater and more miraculous than washing away our sins in His own blood, and is worthy to be called the gift of God, there has not been another kind of offering beforehand such as our empowering to be priests and prophets of God, this is a valuable gift.

[AD 220] Tertullian on Revelation 1:6
Are not even we laics priests? It is written: "A kingdom also, and priests to His God and Father, hath He made us." It is the authority of the Church, and the honour which has acquired sanctity through the joint session of the Order, which has established the difference between the Order and the laity.

[AD 220] Tertullian on Revelation 1:6
" Us, moreover, Jesus, the Father's Highest and Great Priest, clothing us from His own store -inasmuch as they "who are baptized in Christ have put on Christ"-has made "priests to God His Father," according to John.

[AD 258] Cyprian on Revelation 1:6
For I have heard that you have received the ministry of the purpled ones. Oh, happy are you, even sleeping on the ground, to obtain your wishes which you have always desired! You have desired to be sent into prison for His name's sake, which now has come to pass; as it is written, "The Lord grant thee according to thine own heart; " and now made a priest of God over them, and the same their minister has acknowledged it. I ask, therefore my lord, and I entreat by our Lord Jesus Christ, that you will refer the case to the rest of your colleagues, your brethren, my lords, and ask from them, that whichever of you is first crowned, should remit such a great sin to those our sisters, Numeria and Candida. For this latter I have always called Etecusa -God is my witness,-because she gave gifts for herself that she might not sacrifice; but she appears only to have ascended to the Tria Fata, and thence to have descended. I know, therefore, that she has not sacrificed. Their cause having been lately heard, the chief rulers commanded them in the meantime to remain as they are, until a bishop should be appointed. But, as far as possible, by your holy prayers and petitions, in which we trust, since you are friends as well as witnesses of Christ, (we pray) that you would be indulgent in all these matters.

[AD 304] Victorinus of Pettau on Revelation 1:6
"And He made us a kingdom and priests unto God and His Father." That is to say, a Church of all believers; as also the Apostle Peter says: "A holy nation, a royal priesthood."

[AD 735] Bede on Revelation 1:6
And made us a kingdom, etc. Because the King of kings and heavenly Priest, by offering himself for us, has united us to his body, none of the saints is spiritually devoid of the office of priesthood, since he is a member of the eternal Priest.

[AD 1117] Anselm of Laon on Revelation 1:6
Amen. This is a Hebrew word of affirmation.
[AD 1198] Nerses of Lambron on Revelation 1:6
So at the end of this section glory is befitting to Him who brought us to this honor and created so much grace. For we have nothing else to give in exchange, except only glory.
[AD 1198] Nerses of Lambron on Revelation 1:6
made us a kingdom: He made us kings through hope according to the undying promise, because if we endure we shall reign with Him.
[AD 1198] Nerses of Lambron on Revelation 1:6
and priests. in that we continually offer to Him the rational sacrifice of thanksgiving and blessing, heeding the advice, ‘Offer to God a sacrifice of blessing’ instead of irrational sacrifices:
[AD 1349] Nicholas of Lyra on Revelation 1:6
made us a kingdom. That is, to be written as citizens of the kingdom of Heaven.