Revelation 5:2

A strong angel

(αγγελον ισχυρον). One needed (Revelation 10:1; Revelation 18:21) "whose call could reach to the farthest limits of the universe" (Beckwith) and so "with a great voice" (εν φωνη μεγαλη, in a great voice, as in Revelation 14:7; Revelation 14:9; Revelation 14:15, and without εν Revelation 5:12; Revelation 6:10; Revelation 7:2; Revelation 7:10; Revelation 8:13; Revelation 10:3, etc.). See εν ισχυρα φωνη (Revelation 18:2).Proclaiming

(κηρυσσοντα). Present active predicate participle of κηρυσσω, to herald, to preach.Worthy to open and to loose

(αξιος ανοιξα κα λυσα). Worthy by rank and character (cf. John 1:27) as well as by ability (εδυνατο, verse Revelation 5:3), followed by two infinitives (first aorist active) of ανοιγω and λυω, though ινα and the subjunctive can be used after αξιος as in John 1:27. Here αξιος is like ικανος (capable, qualified) as in Matthew 8:8. The articles here (το, τας) refer to the book and the seals in verse Revelation 5:1. It is a husteron-proteron, since the loosing of the seals precedes the opening of the book.