Verse 3
Being (ων). Absolute and timeless existence (present active participle of ειμ) in contrast with γενομενος in verse Hebrews 1:4 like ην in John 1:1 (in contrast with εγενετο in Hebrews 1:14) and like υπαρχων and γενομενος in Philippians 2:6.
The effulgence of his glory (απαυγασμα της δοξης). The word απαυγασμα, late substantive from απαυγαζω, to emit brightness (αυγη, αυγαζω in 2 Corinthians 4:4), here only in the N.T., but in Wisdom 7:26 and in Philo. It can mean either reflected brightness, refulgence (Calvin, Thayer) or effulgence (ray from an original light body) as the Greek fathers hold. Both senses are true of Christ in his relation to God as Jesus shows in plain language in John 12:45; John 14:9. "The writer is using metaphors which had already been applied to Wisdom and the Logos" (Moffatt). The meaning "effulgence" suits the context better, though it gives the idea of eternal generation of the Son (John 1:1), the term Father applied to God necessarily involving Son. See this same metaphor in 2 Corinthians 4:6.
The very image of his substance (χαρακτηρ της υποστασεως). Χαρακτηρ is an old word from χαρασσω, to cut, to scratch, to mark. It first was the agent (note ending =τηρ) or tool that did the marking, then the mark or impress made, the exact reproduction, a meaning clearly expressed by χαραγμα (Acts 17:29; Revelation 13:16). Menander had already used (Moffatt) χαρακτηρ in the sense of our "character." The word occurs in the inscriptions for "person" as well as for "exact reproduction" of a person. The word υποστασις for the being or essence of God "is a philosophical rather than a religious term" (Moffatt). Etymologically it is the sediment or foundation under a building (for instance). In Hebrews 11:1 ψποστασις is like the "title-deed" idea found in the papyri. Athanasius rightly used Hebrews 1:1-58.1.4 in his controversy with Arius. Paul in Philippians 2:5-50.2.11 pictures the real and eternal deity of Christ free from the philosophical language here employed. But even Paul's simpler phrase μορφη θεου (the form of God) has difficulties of its own. The use of Λογος in John 1:1-43.1.18 is parallel to Hebrews 1:1-58.1.4.
And upholding (φερων τε). Present active participle of φερω closely connected with ων (being) by τε and like Colossians 1:17 in idea. The newer science as expounded by Eddington and Jeans is in harmony with the spiritual and personal conception of creation here presented.
By the word of his power (τω ρηματ της δυναμεως αυτου). Instrumental case of ρημα (word). See Hebrews 11:3 for ρηματ θεου (by the word of God) as the explanation of creation like Genesis, but here αυτου refers to God's Son as in Hebrews 1:2.
Purification of sins (καθαρισμον των αμαρτιων). Καθαρισμος is from καθαριζω, to cleanse (Matthew 8:3; Hebrews 9:14), here only in Hebrews, but in same sense of cleansing from sins, 2 Peter 1:9; Job 7:21. Note middle participle ποιησαμενος like ευραμενος in Hebrews 9:12. This is the first mention of the priestly work of Christ, the keynote of this Epistle.
Sat down (εκαθισεν). First aorist active of καθιζω, "took his seat," a formal and dignified act.
Of the Majesty on high (της μεγαλοσυνης εν υψηλοις). Late word from μεγας, only in LXX (Deuteronomy 32:3; 2 Samuel 7:23, etc.), Aristeas, Hebrews 1:3; Hebrews 8:1; Judges 1:25. Christ resumed his original dignity and glory (John 17:5). The phrase εν υψηλοις occurs in the Psalms (Psalms 93:4), here only in N.T., elsewhere εν υψιστοις in the highest (Matthew 21:9; Luke 2:14) or εν τοις επουρανιοις in the heavenlies (Ephesians 1:3; Ephesians 1:20). Jesus is here pictured as King (Prophet and Priest also) Messiah seated at the right hand of God.
Verse 4
Having become (γενομενος). Second aorist middle participle of γινομα. In contrast with on in verse Hebrews 1:3.
By so much (τοσουτω). Instrumental case of τοσουτος correlative with οσω (as) with comparative in both clauses (κρειττων, better, comparative of κρατυς, διαφορωτερον, more excellent, comparative of διαφορος).
Than the angels (των αγγελων). Ablative of comparison after κρειττων, as often.
Than they (παρ' αυτους). Instead of the ablative αυτων here the preposition παρα (along, by the side of) with the accusative occurs, another common idiom as in Hebrews 3:3; Hebrews 9:23. Διαφορος only in Hebrews in N.T. except Romans 12:6.
Hath inherited (κεκληρονομηκεν). Perfect active indicative of κληρονομεω (from κληρονομος, heir, verse Hebrews 1:2), and still inherits it, the name (ονομα, oriental sense of rank) of "Son" which is superior to prophets as already shown (Hebrews 1:2) and also to angels (Hebrews 1:4-58.1.2) as he now proceeds to prove. Jesus is superior to angels as God's Son, his deity (Hebrews 1:4-58.1.2). The author proves it from Scripture (Hebrews 1:4-58.1.14).
https://www.studylight.org/commentaries/eng/rwp/hebrews-1.html
Holman Christian Standard Bible
So He became higher in rank than the angels, just as the name He inherited is superior to theirs.
Aramaic Bible in Plain English
And This One is altogether greater than the Angels, according to how much more excellent than theirs is The Name which he possesses.
Smith's Literal Translation
Being so much better than the angels, inasmuch as he has inherited a more distinguished name than they.
Godbey New Testament
being so much greater than the angels, that he has inherited a name so much more excellent than they.
Mace New Testament
He is so much superiour to the angels, as the authority he possesses is more excellent than theirs.
Worsley New Testament
Being as much superior to the angels, as He inheriteth a name more excellent than they.