Folklore tends to have everyday items that have either good or bad properties. Because my villains in Benandante are taken from folklore and myth, it makes sense that common items would become weapons.

Water from Bath, England is said to have healing properties. Wolfsbane, a plant that is said to hurt or kill werewolves. Garlic, a deterrent to vampires and other similar blood sucking monsters. And quicksilver, or mercury, another weapon against werewolves and possibly other creatures that lurk in the night.

Mrs. Euphemia Beaufort and her Benandante brethren have access to elemental spells/magic in the Netherworld. But in our world, they have no special powers other than some healing or protective charms/spells. In order to fight the evil invading London, Mrs. Beaufort turns to the items from folklore that are said to harm the creatures. Just because these are common items doesn't mean they are easy for her to procure, however.