Footnote: Radiant: the Hebrew word translated “radiant” is spelled like the term for “horns.” Thus the artistic tradition of portraying Moses with horns.
"Moses came down, after this, from Mount Sinai, bearing with him the two tablets on which the law was written; and his face, although he did not know it, was all radiant after the meeting at which he had held speech with God" (Knox Bible).
"Cumque descenderet Moyses de monte Sinai, tenebat duas tabulas testimonii, et ignorabat quod cornuta esset facies sua ex consortio sermonis Domini" (Latin Vulgate).
The Douay-Rheims Bible famously reports that Moses' face "was horned from the conversation of the Lord."
Menahem Haran reviews the historical developments that led to the Vulgate and DR rendering "was horned," but then Haran writes:
However, most commentators, both the older and the more contemporary, have already concurred that the verse refers to rays of light radiating from the brilliance of Moses' face, just as in Habakkuk 3.4 it is said of God himself: 'rays of light, qarnayim [cognate with qaran], flash from his hand' (before which we read that 'his brightness is like the light'). The splendour surrounding the image of God is alluded to in several additional biblical passages: the seventy elders of Israel saw God 'and under his feet there was the likeness of a pavement of sapphire, like the very sky for purity' (Ex. 24.10), Ezekiel saw 'radiance all about him' (Ezek. 1.27-28), while the psalmist describes the Lord as 'wrapped in light as with a garment' (Ps. 104.2; see also below). Something of the divine radiance was imparted, then, to Moses' face, which thereafter also shone. Later on the passage relates how the people, being repulsed by this radiance, were afraid to get close to Moses, but he dispelled their fears, and after telling them the Lord's message he put a masweh over his face. The substantive masweh, also mentioned only in this passage, is mostly explained, according to the context, as a veil or scarf hung over the face, though the etymology is uncertain.
To understand the wider context of Haran's remarks, see Barrick, W. Boyd, John R. Spencer, and Gösta W. Ahlström. In the Shelter of Elyon: Essays on Ancient Palestinian Life and Literature in Honour of G.W. Ahlström. Sheffield: JSOT Press, 1984. Pages 159-160.