Exegesis:

kai ēgeiren keras sōtērias hēmin ‘and he has raised up a horn of salvation for us.’

egeirō ‘to wake,’ ‘to raise,’ ‘to raise up’ (in the active), ‘to rise’ (in the passive); when used with a personal object it may be rendered ‘to bring into being,’ ‘to cause to appear,’ and it is implied that the object will have to fulfil a task. This meaning fits the interpretation of keras sōtērias, given below.

keras sōtērias is translated literally by the great majority of translators. In the Old Testament ‘horn’ is often a symbol of might and power, cf. Jer. 48.25; Zech. 1.18ff; Ez. 29.21. But in 2 Sam. 22.3 (= Ps. 18.2) God is called the “horn of my salvation”, and Strack-Billerbeck (II, 111) quotes ancient Jewish prayers where the same expression refers to the davidic Messiah; hence translations like “a mighty Savior” (An American Translation, see also Translator’s New Testament, New English Bible, Moffatt, The Modern Speech New Testament). keras.

en oikō Dauid paidos autou ‘in the house of David, his servant’; this addition shows that the preceding clause is a reference to the davidic Messiah.

Translation:

Horn of salvation. A literal rendering (though possible in some languages, e.g. in Uab Meto which can use ‘horn’ metaphorically for ‘hero’) is, as a rule, impossible. Yet the tendency seems to be strong to use such a rendering, even when unidiomatic, misleading or incomprehensible in the language concerned, and to disregard existing acceptable cultural equivalents (e.g. ‘tusk,’ suggesting ‘champion/hero,’ in Balinese). In the material investigated only two translators render “horn” by another metaphor, i.e. Phillips, “standard”, and Knox, “sceptre”. Some non-metaphorical renderings are ‘one who is very strong, who will save us/people’ (cf. Apache, Tboli), ‘salvation-hero’ (Kannada); or, following the non-personal interpretation, ‘token of happiness/salvation’ (Toraja-Sa’dan), or (combining such a rendering with a simile), ‘caused the help/salvation to grow like an animal’s horn’ (Sranan Tongo). For salvation, or, ‘Saviour,’ cf. on v. 47.

In the house of, cf. on v. 27, for his servant David, or ‘David, who is his servant,’ cf. on v. 32.

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.