Short story where magic is powered by secrets

Question

I'm looking for a short story I read 2-5 years back. I'm pretty sure it was in a anthology of short stories about magic, possibly about wizards specifically. I believe that the anthology was recent.

In the story, wizards get their magical power from a single secret they keep. The fewer people know the secret, the more powerful their magic is, and if another wizard learns your secret they have power over you. The plot of the story focuses on the protagonist, a very powerful wizard, fending off an attempt from a rival to discover their secret. The plot involved tricking or enchanting a young bar maid (or similar) to become enamored with the wizard.

At the end, the secret is revealed to be

that the wizard is actually a woman.

Answer 1

This may be Marion Zimmer Bradley's "The Secret of the Blue Star," part of the Thieves World anthology.

Marion Zimmer Bradley later took her sorcerer Lythande (pronounced “lee-thond”), first introduced in this tale, and produced a book-length collection of stories about the character, titled Lythande. Lythande is an adept of the Blue Star, and such wizards are bound by some of the most interesting rules of magic ever presented in a fantasy story. Each adept must choose a secret to be the source of his power—the greater the secret, the greater the power. But if that secret is discovered by a fellow adept, the rival can steal all of that wizard’s magic. It’s a brilliant conceit that fits perfectly with the cloak-and-dagger milieu of Sanctuary, a city roiling with dark prophecies, bitter rivalry, and life-or-death intrigue.

I vaguely remembered this story from reading the anthology as a child, but it took searching for short story wizard secret "is a woman" and coming upon the description in a review of The Way of the Wizard to remember the title.