BANE

:''For other uses of the word bane, see bane (disambiguation).''
The meaning of 'bane' as an English form of , the bringer of ruin, dates only from 1577. Now an affliction, curse, evil, ill, plague, scourge or woe, in Old English ''bana'' had a more specific and immediate meaning, of "slayer", "murderer."
Possibly derived from nordic languages brought to britain by the Vikings, where "bane" (in swedish for example) means "something causing your death".
In the Middle Ages, a number of plants were thought to have poisonous or prophylactic qualities, which would have dire consequences (Henbane) or liminal ones, like "Wolfsbane" ("Aconite", Aconitum). Aconite is thoroughly poisonous, but no one would bait a wolf-trap with it. So its qualities as a "bane" must be protective, for the wolf is more dangerous than a mere ravening carnivore. Many medieval Europeans believed that they could become werewolves. Aconite was the toxic entheogen that could keep the dire transformation from happening. At a later date, milder poisoning was thought to trouble sheep in the U.S. southeast if they strayed into woodland and nibbled ''Kalmis latifolia'', or "sheep's bane").