I have searched my electronic copy of Biblia Sacr JUXTA Vulgatam Clementinam and it seems in all three cases I could find, lucifer means the morning star (the planet Venus) or possibly just the day in one instance. It seems to be used as an image which suits both the Devil and Christ. It is only Capitalized as a personification in Isaiah where it seems to be describing the Devil.
“How you are fallen from heaven,
O Day Star, son of Dawn!
How you are cut down to the ground,
you who laid the nations low! (Isaiah 14:12, ESV)
12 Quomodo cecidisti de cælo, Lucifer, qui mane oriebaris ?
corruisti in terram,
qui vulnerabas gentes ? (Isaiah 14:12)
'lucifer' is used for the word 'morning' in Job:
And your life will be brighter than the noonday;
its darkness will be like the morning. (Job 11:17, ESV)
17 Et quasi meridianus fulgor consurget tibi ad vesperam ; et cum te consumptum putaveris, orieris ut lucifer. (Job 11:17)
'lucifer' is also used for the 'morning star' (Venus) in 2Peter:
And we have the prophetic word more fully confirmed, to which you will do well to pay attention as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts (2 Peter 1:19, ESV)
19 Et habemus firmiorem propheticum sermonem : cui benefacitis attendentes quasi lucernæ lucenti in caliginoso donec dies elucescat, et lucifer oriatur in cordibus vestris : (2Peter 1:19)
'luciferum' is also used for the 'morning star' (Venus) in Psalms 110 and Job 38:
Your people will offer themselves freely on the day of your power,in holy garments; from the womb of the morning, the dew of your youth will be yours. (Psalms 110:3, ESV)
3 Tecum principium in die virtutis tuæ in splendoribus sanctorum :
ex utero, ante luciferum, genui te. (Psalms 110:3)
Note: The ESV translates the 'morning star' more generally as the actual constellations (Mazzaroth) and not Venus:
Can you lead forth the Mazzaroth in their season,or can you guide the Bear with its children? (Job 38:32, ESV)
32 Numquid producis luciferum in tempore suo,
et vesperum super filios terræ consurgere facis ? (Job 38:32)