Aiguillette

https://solitarypaganism.com/mythology/aiguillette/
A knotted loop of thread, also called a ligature, which witches were said to use to cause impotence, and perhaps even castration, in men; barrenness in women; and general discontent in marriage.

The aiguillette also served to bind couples in illicit amatory relationships.

The phobia of the ligature, or fear of satanic castration, was widespread in 16th-century France.

It was believed that at the instant when a priest blessed a new marriage, the witch slipped behind the husband, knotted a thread and threw a coin on the ground while calling the Devil.

If the coin disappeared, which all believed to mean that the Devil took it and kept it until Judgment Day, the couple was destined for unhappiness, sterility and adultery.

Couples living in Languedoc were so fearful of satanic castration that not 10 weddings in 100 were performed publicly in church.

Instead, the priest, the couple and their parents went off in secret to celebrate the sacrament.

Only then could the newlyweds enter their home, enjoy the feasting and go to bed. At least one physician, Thomas Platter, concluded that the panic was so bad that there was a local danger of depopulation.