Apostrophe: Pure or personified
From English Composition and Rhetoric, by Alexander Bain; W. Davidson; Practical Rhetoric, by Albert Raub:
Apostrophe (Latin apo, from strophe, ‘a turning’) is a figure by which the speaker turns from the subject of discourse and addresses some other person or thing:
O Death, where is thy sting?
O Grave, where is thy victory?—I Corinthians 15:55
I. It supposes intensity of emotion.
Is this a dagger which I see before me,
The handle toward my hand? Come, let me clutch thee!
I have thee not, and yet I see thee still. —Shakespeare, Macbeth, Act 2, Scene 1
There can be no apostrophe without intense feeling.
II. It may exist in either of two forms.
A. Pure apostrophe
O my son Absalom, my son, my son Absalom! would God I had died for thee, O Absalom, my son, my son!—II Samuel 18:33
B. Apostrophe combined with personification
Death, be not proud, though some have called thee / Mighty and dreadful, for thou art not so
—John Donne, “Holy Sonnet X”