A.T. Robertson Commentary Luke 1:79

"To shine upon them that sit in darkness and the shadow of death; To guide our feet into the way of peace." — Luke 1:79 (ASV)

To shine upon (επιφανα). First aorist active infinitive of επιφαινω (liquid verb). An old verb to give light, to shine upon, like the sun or stars. See also Ac 27:20; Titus 2:11; 3:4.

The shadow of death (σκια θανατου). See Ps 107:10, where darkness and shadow of death are combined as here. Cf. also Isa 9:1. See on Mt 4:16. To guide (του κατευθυνα). Genitive of the articular infinitive of purpose. The light will enable them in the dark to see how to walk in a straight path that leads to "the way of peace." We are still on that road, but so many stumble for lack of light, men and nations.