[QUOTE=spiralI understand French & German satanist knives are well recorded from at least in the 3rd quarter of the 19th century. But certanly many are later.l[/QUOTE]
Spiral, why "certainly"? I am not sure what you are basing this assuption on. Have you seen or do you have any links to photos of "satanic" blades that pre-date the late 19thC.
I am well aware of the stories of Catherine La Voisin, but much of her legend is just that and beyond any definable fact. She apparently claimed to have sacrificed 2500 children, but there was hardly a rash of missing children in her area during her run in France. The 'black mass" is not necessarily a satanic thing, it is just a rebelious anti-Christian thing. It doesn't necessarily require the belief in Satan as one's god nor the evil doings such as child sacrifice that the stories of satanism would have one believe were common practice for these cults. As i stated earlier "satanic" is a loaded term that is probably best left behind.
This could still be meant as a ritual weapon i am leaning more towards the Hunchback attribution.