Fantasy. Heroine finds a word of power (used by magic system) after solving a puzzle in a garden. City is guarded by angels, avian people? Read around 2010.

[Scribs]

I read this book about a decade ago, and it was old even then. I don't remember a lot of details.

The book is set in a fantasy city guarded by angels...avian people(?) and the magic system uses words of power. The girl solves a puzzle in a garden and acquires a word of power. There was also a demon/entity/god trapped underneath a... temple? I remember he was very charming.
And that's about it. Please help if you can!

[Rainbowheart]

Is this book for kids, teens, or adults?