This was a guide to writing (not a style manual) written by a famous female author or poet. In it, she gives advice on writing, and she does it using unusual, imaginative prose (I can’t remember enough to quote, but something like “Write the words not too lightly and sparingly”). The whole book read like that.
I’m sorry I can’t give more details, but it’s been 15 years since I leafed through it, and I didn’t write any details down. Any ideas?