This section is from the book "Ancient Legends, Mystic Charms, And Superstitions Of Ireland", by Jane Francesca Wilde. Also available from Amazon: Ancient Legends, Mystic Charms, And Superstitions Of Ireland.
Fairy darts are generally aimed at the fingers, causing the joints to swell and grow red and inflamed. An eminent fairy-woman made the cure of fairy darts her speciality, and she was sent for by all the country round, and was generally successful. But she had no power unless asked to make the cure, and she took no reward at the time; not till the patient was cured, and the dart extracted. The treatment included a great many prayers and much anointing with a salve, of which she only had the secret Then she proceeded to extract the dart with great solemnity, working with a small instrument, on the point of which she finally produced the dart. This proved to be a bit of flax artfully laid under the skin by the malicious fairies, causing all the evil, and of course on seeing the flax no one could doubt the power of the operator, and the grateful patient paid his fee.