Past perfect simple - strange usage

By definition, past perfect simple tense "expresses an action taking place before a certain time in the past".

I have a hard time to understand why Terry Pratchett used it in the sentence:

"The scythe that had done the work leaned against the gnarled bole of a pear tree."

Can I kindly ask for an explanation? I can't see any reason for it because no exact information about certain time in the past is given.

Thank you in advance.

Solution 1:

Try inserting the word "now" in the second half of the sentence:

The scythe that had done the work [now] leaned against the tree.

Those are two different actions being described, taking place at two different points in the past.

1. First (earlier), the scythe did some work.

2. THEN (later) it leaned against the tree, like so.