James 1:12 (NA28): Μακάριος ἀνὴρ ὃς ὑπομένει πειρασμόν, ὅτι δόκιμος γενόμενος λήμψεται τὸν στέφανον τῆς ζωῆς ὃν ἐπηγγείλατο τοῖς ἀγαπῶσιν αὐτόν.
F.J.A. Hort favors the rendering "happy" for Μακάριος rather than "blessed" (The Epistle of St. James: The Greek Text, pages 19-22); I found nine occurrences of the phrase Μακάριος ἀνὴρ in the LXX. Some instances include Psalm 1:1; 32:2; 34:8. On the other hand, Ben Witherington III likes "blessed" in this context; for one thing, he states that James is not talking about eudaimonia here. See Witherington III, Letters and Homilies for Jewish Christians: A Socio-Rhetorical Commentary on Hebrews, James, and Jude.
Herbert Bateman IV suggests that James employs ἀνὴρ and ἄνθρωπος as overlapping relations (synonyms) to designate both men and women. See Bateman IV, Interpreting the General Letters: An Exegetical Handbook, page 148. BDAG posits that the meaning is "someone" in this verse.
Translate ὃς, "who"; ὑπομένει (present active indicative third person singular of ὑπομένω) modifies πειρασμόν (accusative masculine singular of πειρασμός). The verb form ὑπομένει occurs twice in the GNT: see 1 Corinthians 13:7. The anarthrous πειρασμόν could be indefinite ("a trial") or qualitative in force ("trial/tribulation").
ὅτι is causal ("because"); δόκιμος γενόμενος-the second word is a temporal/adverbial aorist participle ("when or "after having become") whereas the adjective δόκιμος is nominative masculine singular ("approved" or "tested"). Compare James 1:3.
λήμψεται is future middle indicative third person singular of λαμβάνω ("I take, receive"). The meaning here is likely passive (i.e., receive).
Scot McKnight makes these observations (NICNT on James):
δόκιμος γενόμενος, roughly “in, or by, becoming approved.” The “has stood” is a strong translation of the aorist middle participle. The aorist here is less concerned with the state or the process, and more with the “thatness” of “being dokimos.” We might translate: “Blessed is the person … because, as the approved one, that person will receive.…” This adjectival participial clause modifies the implied subject of the verb λήμψεται.Concerning τὸν στέφανον τῆς ζωῆς, I will reference BDAG and its entry for στέφανος:
award or prize for exceptional service or conduct, prize, reward fig. (LXX; ApcEsdr 6:17, 21 p. 31, 26 and 31 Tdf.; as symbol of victory ANock, ClR 38, 1924, 108 n. 11). In 1 Cor 9:25 (ref. to incorruptibility) and 2 Cl 7:3 (s. 1 above) the ref. to crown or wreath is strongly felt, but in the pass. that follow the imagery of the wreath becomes less and less distinct, yet without loss of its primary significance as a symbol of exceptional merit (Ael. Aristid. 27, 36 K.=16 p. 397 D.: τῶν ἀθανάτων στ.; PSI 405, 3 [III b.c.]; Danker, Benefactor 468–71). Obj. gen. τ. δικαιοσύνης for righteousness (recognition of uprightness is a common topic in Gr-Rom. decrees; s. δικαιοσύνη 3a; on the implied exceptional character of the wearer of a crown s. LDeubner, De incubatione capitula duo, 1899, 26) 2 Ti 4:8 (on posthumous award s. New Docs 2, 50; cp. Soph., Phil. 1421f of glory after suffering). W. epexegetical gen. (this is the sense of στ. δικαιοσύνης EpArist 280; TestLevi 8:2) ὁ στέφ. τῆς ζωῆς (s. ζωή 2bβ) Js 1:12; Rv 2:10; cp. 3:11; ὁ τῆς ἀφθαρσίας στ. MPol 17:1; 19:2; ὁ ἀμαράντινος τῆς δόξης στ. 1 Pt 5:4 (cp. Jer 13:18 στ. δόξης; La 2:15; cp. 1QS 4:7; 1QH 9:25; τῆς βασιλείας στ. Hippol., Ref. 9, 17, 4).—ἐλευθέριος στ. AcPl Ha 2, 31.—MBlech, Studien zum Kranz bei den Griechen 1982 (lit.).—Schürer III/1 103f, n. 60 (lit). Pauly-W. XI 1588–1607; Kl. Pauly III 324f; BHHW II 999f.—New Docs 2, 50. DELG s.v. στέφω. M-M. EDNT. TW. Sv.
ὃν-relative pronoun that is accusative masculine singular of ἐπηγγείλατο-this verb is aorist middle indicative third person singular of ἐπαγγέλλομαι ("I promise, profess"). Compare James 2:5; 1 John 2:25. Chris Vlachos suggests that the implied subject of the verb is God.
τοῖς ἀγαπῶσιν-present active participle dative plural masculine of ἀγαπάω functioning substantivally (Vlachos).
αὐτόν-accusative singular masculine third person.