From what i can tell this category of "Dague Romantique" seems a bit vague, but i would say that your example seems to fit well within it. I would take the "carried by prostitutes" line with a grain of salt as so far i can only find that as a line from sellers to entice sale. Do you have an academic reference to this use. Here is a link to a similar style dagger (different figure and motif) that was claimed "satanic" in nature.
http://www.vikingsword.com/vb/showth...ack+notre+dame
Here are some examples of what i could find on the web also described as "Dague Romantique".