This very intriguing looking dagger seems to me 'made in the 19th century style' of romantic theme or allegorical daggers of these times. The term 'romantic' derives from the Gothic themes and novels popular in the time, and one of the popular subjects in image was of course Notre Dame cathedral. The gargoyle figure corresponds to these representations of lurking evil which decorate parts of the cathedral, with these legendary creatures usually a dragonlike beast with batlike wings.
Other daggers of this type have been discussed (such as the spirited discussion David linked from 2007) in which the Notre Dame theme also occurs, and there seem to be other theme type daggers of the mid to latter 19th century which form basis for many of these 20th century interpretations, as well as many of the French associations.
The link to the macabre may derive from the theme daggers produced in 16th century, where the 'dance of death' allegory was from the book published by Hans Holbein (the younger) in Lyon, and applied to the decoration of these daggers.
While many of these daggers invoke a foreboding appearance that seems to inspire many to label them satanic, thinking that these might be examples of the athame daggers used ceremonally, and better termed 'occult', these seem to be simply interpretive examples of the earlier theme daggers.
It seems some of these have brought some pretty amazing results when sold, however typically they seem to have had early blades from other weapons which added support to interesting provenance...but still the stories along with some of these are apocryphal at best.
The mention of fraternal and secret societies is well placed, and often unusual themed accoutrements have been used in all manner of regalia, so these kinds of attribution always have a degree of plausibility......by thier very nature though, research is pretty difficult
Still, these are intriguing in appearance and interesting pieces, always great for conversation!!