There seems to be a great deal of confusion over who this mighty angel is in chapter ten of the Apocalypse. Some conclude he is the Emperor Justin who ruled in favor of orthodoxy and against the Arians concerning the deity of Jesus. Others say he is evil and represents the papacy and the little book his cannons and decrees. Still others want to say the angel is Luther and the other reformers of his day and the little book is represents the Protestant doctrines of reformation. Nevertheless, all of these interpretation represent the newspaper exegetes of their day, and what they say is purely subjective in nature, without an ounce of objective evidence. The proof of the pudding is in the eating, and in this case the eating has to do with the word of God. The Scriptures tell us who this angel is, and what was really in his hand.
In Revelation 10:1 John tells us that he saw another mighty angel. It seems to me that we were introduced to the angel in Revelation 5:2, and will meet him again in Revelation 18:21. He also appears in Revelation 8:3, but there performs duties of the High Priest. In the context of the Apocalypse revealing Jesus (Revelation 1:1) in his three offices: High Priest, Prophet and King, I believe Revelation 10:1 reveals Jesus as the Prophet who was to come (cf. Deuteronomy 18:15-19; Matthew 21:11; John 6:14). This mighty Angel under the Old Covenant is referred to as the Angel (Messenger) of the Covenant (Malachi 3:1), the Angel of the Lord (Genesis 16:7), the Angel of his Presence (Isaiah 63:9) and is even called the LORD, meaning YHWH (Genesis 19:24). The Septuagint calls him the Angel of the Great Council in Isaiah 9:6, but in the Hebrew the same is called: “Wonderful, Counselor” and then the verse goes on to call him “the Mighty God, the Everlasting Father, the Prince of Peace” (Isaiah 9:6), but in Genesis 48:16 he is simply called Angel, but Jacob also describes him there as his Redeemer! This Angel (Messenger) in Revelation 11:3 claims he will give power to his two witnesses. What angelic being has witnesses? The Lord has witnesses (Isaiah 43:10-12), but angelic beings do not.
John calls him another mighty Angel, which has led some to conclude he couldn’t be the same as the one referred to in Revelation 5:2 or 18:21. However, the Greek word for another is allos (G243), i.e. another of the same kind as the one we already met in Revelation 5:2. This means he is not another, heteros (G2087), meaning another of a different kind (see Galatians1:6 for this argument). Therefore, I believe this one is another (G243) with respect to his office. Here, he is the Prophet, but there (Revelation 5:2 and 8:3) he is the High Priest. He is called an Angel to indicate a new message is brought from heaven. The fact that he is also mighty indicates the work he must do was beyond the ability of the labor of man.
Moreover, we are told that this Angel was clothed in a cloud with a rainbow upon his head (Revelation 10:1). A cloud or clouds are mentioned seven times in the Apocalypse, and each time they seem to point to Jesus (Revelation 1:7; 10:1; 11:12; 14:14 (twice); 14:15 and 14:16). Jesus was clothed in a cloud in Acts 1:9, and the Presence of God is referred to with clouds under the Old Covenant in 1Kings 8:10-13 and Psalm 104:3. As for the rainbow, it is first mentioned in Genesis 9:13 to comfort those the Lord had saved from the Flood. It was a message of peace, in that God would never destroy the earth and all men upon it ever again, and the rainbow with this connotation represents the glory that envelops the Throne in heaven and he that sit thereon (Revelation 4:3; cf. Ezekiel 1:28).
Finally, John describes the Angel’s face and feet. His face was bright like the sun, which we see elsewhere as a description of Jesus (Revelation 1:16; 18:1). The preacher tells us that light is sweet, and it is a pleasant thing for the eyes to behold the sun (Ecclesiastes 11:7). So, it is a sweet thing and a pleasant thing for John to both behold this Angel’s face and that of Jesus during the Transfiguration (Matthew 17:2). As for his feet, they are described similarly in Revelation 1:15 for that of Jesus.