Exegesis:

aggelos kuriou, cf. on 1.11.

epestē autois ‘stood by them,’ denoting a movement towards the shepherds, hence “came upon them” (Translator’s New Testament), and implying a note of suddenness.

ephistēmi usually in present or aorist tense only, ‘to stand by,’ ‘to approach,’ ‘to appear,’ often of the appearing of divine beings in dreams and visions.

doxa kuriou perielampsen autous ‘the splendour of the Lord shone around them.’

doxa ‘brightness,’ ‘splendour,’ ‘magnificence,’ ‘honour’; here it appears visibly as a radiant light, cf. Zürcher Bibel, Lichtglanz. In the Septuagint doxa kuriou translates kavod yahwe(h), God’s visible presence, cf. e.g. Ex. 16.10; 24.16; 40.34f.

perilampō ‘to shine around someone.’

kai ephobēthēsan phobon megan lit. ‘and they feared (with) a great fear’; phobon megan is accusative of content (cf. on v. 8) and here has the function of an adverb of degree, cf. “greatly afraid” (Translator’s New Testament).

Translation:

For the Lord (also in vv. 15, 22ff, 26, 29, 39) see on 1.6 sub (c).

Appeared to them. The verb (in the original differing from the one used in 1.11) has also been rendered, ‘came and stood at the side (or, in the midst, or, in front) of’ (cf. Sranan Tongo, Kannada, Tboli).

The glory of the Lord shone around them, or more analytically, ‘shone-on them, it surrounded them’ (Kituba). Often the expression usually rendering glory clearly conveys the concept of ‘brightness,’ ‘radiance’; then it may be better to render the verb simply by ‘was around them,’ ‘enveloped/surrounded them,’ cf. ‘great the brightness … all around them’ (Tboli). Elsewhere the usual rendering does not go idiomatically with ‘to shine’; then it may be possible to say, ‘the radiance of the majesty … shone-on them all-around’ (Balinese), or to shift to a simile, e.g. ‘the greatness/majesty … was around (or, enveloped) them like a flame/radiance.’

They were filled with fear, or, ‘they became very afraid,’ refers to the effect of the two preceding events; hence a connective like, ‘therefore,’ ‘consequently,’ ‘so’ (cf. Javanese, Batak Toba).

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.