Blaze is Gilan's bay mare, meaning that her body, neck, face and legs are brown, with a black mane, tail and stockings above her hooves. She also has a long strip of white from her nose, up between her eyes, and stopping just before the mane; this is a "blaze".
Like the Ranger who rides her, she is tall and easily amused. She, like all Ranger horses, will also listen and respond to a single touch or sound. They are all quite similar in their personalities. Blaze, more often than not, is mistaken for a male in several books.