All forgot for recollecting
paltry One
She capitalizes 'One' like a proper noun—this person isn't paltry to her, the world thinks they are. The irony sits in the grammar.
stranger's New accompanying
The awkward phrasing is deliberate—'accompanying' as a noun makes the relationship itself the thing possessed, not the person.
Grace of rank
'Grace' appears twice but means social standing, not spiritual favor. She's listing what she gave up: status and money.
her faces dwindled
'Her' is home personified—the familiar faces of family members literally shrink in importance. Not 'their faces' but home's faces.
timid pebble
She's small, the beloved is an ocean. But notice: she 'dropped' her fate deliberately—this is chosen submission, not accident.
Prove myself of Thee
Not 'to Thee' but 'of Thee'—she wants to be made of the beloved's substance, become part of them. Alchemical language.