Ideally, I would like the cover depict a scene from the book: At sunset on a Chinese-style sailing/Junk ship with a leather balloon in place of mast and sails, in the sky far above a canyon at sunset.
The two main characters should by standing back to back each with a sword (rapiers) in one hand, a flintlock pistol in the other -- 1) a black woman in her mid-twenties with wavy, red hair, a black, wide brimmed hat with a red feather, and classically steampunk attire (corset, trousers, boots, etc). She has mismatched eyes, one green, one lightbrown/yellowish. 2) An ethnically ambiguous man in his mid-20's with waist-length black hair, a black long coat, vest, and trousers, and a white shirt. The duo should have some battle damage. She is left handed, he is right handed
They should surround be surrounded by harpies -- flying, sickly looking women with black-feathered wings and talons. Despite the wings, they move through the air like water, and should have an ephemeral look to them.