I agree this is quite a rare word. The online Oxford labels it as literary, but other dictionaries generally have no usage note.
Mostly it is used to mean cheat or defraud. A fairly recent, non-literary, use was in an opinion piece by Nick Cohen in the
Guardian in February this year:
The Sun and much of the rightwing press would rather tell us fairy stories with happy-ever-after endings than admit their mistake in selling Brexit to their cozened readers.
I'll change
cozened and
cozening to rare status.
Cozen has always been rare.
