"Sophy, shut up in a back room, glancing down from her work into a sooty little strip of garden with a pump in it. But there I always found her, the same bright housewife; often humming her Devonshire ballads when no strange foot was coming up the stairs, and blunting the sharp boy in his official closet with melody.

I understand that there is a play of words (blunt vs. sharp) but it is not clear to me what it means. I challenge members for a translation that does not speak ill of Sophy's singing.

I think the idea is that she's softening the sharp boy's heart, making him keep less of an eye open for the main chance, and more susceptible to tender emotions.

Bingley

Dear Bingley: I'm not sure I know all the implications of
"the main chance".

advance of self-interest, not necessarily in the most ethical manner.

Bingley

Thank you for the quotation, Dr Bill. It took me back to David Copperfield to re-read the last few chapters just for the sake of the happy ending! All the loose ends tied up in inimitable fashion!