It is believed that to know the name of a particular fairy could summon it to you and force it to do your bidding. The name could be used as an insult towards the fairy in question, but it could also rather contradictory be used to grant powers and gifts to the user.
But the Fairies can also, out of affection or gratefulness towards a human, bestow almost any gift upon their favourites:
Sometimes their marvelous skill is communicated to mortals, sometimes they come in person to assist. If a smith, wright, or other tradesman catches them working with the tools of his trade (a thing they are addicted to doing) he can compel them to bestow on him the Ceaird Chomuinn, or association craft, that is to come to his assistance whenever he wants them. The gift remained even after he had told how he acquired it. One undoubted gift of the fairies was that of skill in music, and there are many stories of how the MacCrimmons, the most famous family of Scottish pipers, were given their skill by the gift of a black chanter to a despised younger son of the family. The gift was accompanied by tuition. Many songs and airs have come out of fairy hills and have survived the change into the human world.
Assistance in the daily work
Some Faerie races are famous for helping humans like the Brownies that clean our homes, or the Knockers that help the miners locate precious metals underground. They will also give cows stolen for the purpose from others, keep cattle from wandering into crops at night, assist peasants in spring and harvest work, … Work left near the hillocks over night has been found finished in the morning.
Faerie are said to give men magic objects in returns for their blessings. Lusmore, a young britton was given several gifts for helping the Korrigans to finish a song they were cursed by a witch to sing and dance until they find the end. He then received a magic Biniou (pipes) that plays music by itself, a magic cauldron that turns stones into delicious dishes and a special bath that preserves the youthness. Other tales are based on the gift of magic weapons to heroes and warriors (Siegfried, Arthur, Odin …). According to the Norse Edda, The dwarves are most often noted for being extremely skilled smiths and craftspeople. Among the many magic treasures created by them are: Mjollnir, the hammer of Thor; Gleipnir, the chain that bound the wolf Fenrir when all other fetters failed; Skidbladnir, a ship which belongs to Freyr and always has a favorable wind; Gungnir, the spear of Odin; Draupnir, a ring owned by Odin; the Brisingamen, a magnificent necklace owned by Freya; and the long, golden hair of Sif, Thor’s wife.
The side effect
In most cases, the benefit of the gift goes ultimately to the Fairies themselves. Their gifts have evil influence connected with them, and, however inviting at first, are productive of bad luck in the end. It is wiser not to resort to their company or their kindness. When they come to a house to assist at any work, the sooner they are got rid of the better. If they are hired as servants their wages at first appear trifling, but will ultimately ruin their employer. It is unfortunate even to encounter any of the race, but to consort with them is disastrous in the extreme.