This nicely constructed garage sale-find appears to be some sort of atomizer-type device. Unscrew the lid using the wingnut, pour in your choice of liquid, pump the handle to pressurise and activate using the thumb-activated trigger. There doesn't appear to be any identifying marks on it at all. At first I thought it might be some sort of torch but the stamped hearts on the handle would suggest something more feminine. I'll keep polishing it though, it really seems a likely home for a genie.