IRON – the anti-faerie metal –
Here is an example of an intrepid Fiddler using a small iron dirk to Earth an evil faerie like some interdimensional lightning conductor …..
Iron or steel, in the shape of needles, a key, a knife, a pair of tongs, an open pair of scissors, or in any other shape, if placed in the cradle, secured the desired end. In Bulgaria a reaping-hook is placed in a corner of the room for the same purpose. I shall not stay now to discuss the reason why supernatural beings dread and dislike iron. Edwin Sidney Hartland [b. 1848 d. 1927] New York: Scribner & Welford 
The Fiddler and the Bogle of Bogandoran
Scottish Fairy and Folk Tales, by George Douglas, ,
“Late one night, as my grand-uncle, Lachlan Dhu Macpherson, who was well known as the best fiddler of his day, was returning home from a ball, at which he had acted as a musician, he had occasion to pass through the once-haunted Bog of Torrans. Now, it happened at that time that the bog was frequented by a huge bogle or ghost, who was of a most mischievous disposition, and took particular pleasure in abusing every traveller who had occasion to pass through the place betwixt the twilight at night and cock-crowing in the morning. Suspecting much that he would also come in for a share of his abuse, my grand-uncle made up his mind, in the course of his progress, to return the ghost any civilities which he might think meet to offer him. On arriving on the spot, he found his suspicions were too well grounded; for whom did he see but the ghost of Bogandoran apparently ready waiting him, and seeming by his ghastly grin not a little overjoyed at the meeting. Marching up to my grand-uncle, the bogle clapped a huge club into his hand, and furnishing himself with one of the same dimensions, he put a spittle in his hand, and deliberately commenced the combat. My grand-uncle returned the salute with equal spirit, and so ably did both parties ply their batons that for a while the issue of the combat was extremely doubtful. At length, however, the fiddler could easily discover that his opponent’s vigour was much in the fagging order. Picking up renewed courage in consequence, he plied the ghost with renewed force, and after a stout resistance, in the course of which both parties were seriously handled, the ghost of Bogandoran thought it prudent to give up the night.
“At the same time, filled no doubt with great indignation at this signal defeat, it seems the ghost resolved to re-engage my grand-uncle on some other occasion, under more favourable circumstances. Not long after, as my grand-uncle was returning home quite unattended from another ball in the Braes of the country, he had just entered the hollow of Auldichoish, well known for its ‘eerie’ properties, when, lo! who presented himself to his view on the adjacent eminence but his old friend of Bogandoran, advancing as large as the gable of a house, and putting himself in the most threatening and fighting attitudes.
“Looking at the very dangerous nature of the ground where they had met, and feeling no anxiety for a second encounter with a combatant of his weight, in a situation so little desirable, the fiddler would have willingly deferred the settlement of their differences till a more convenient season. He, accordingly, assuming the most submissive aspect in the world, endeavoured to pass by his champion in peace, but in vain. Longing, no doubt, to retrieve the disgrace of his late discomfiture, the bogle instantly seized the fiddler, and attempted with all his might to pull the latter down the precipice, with the diabolical intention, it is supposed, of drowning him in the river Avon below. In this pious design the bogle was happily frustrated by the intervention of some trees which grew on the precipice, and to which my unhappy grand-uncle clung with the zeal of a drowning man. The enraged ghost, finding it impossible to extricate him from those friendly trees, and resolving, at all events, to be revenged upon him, fell upon maltreating the fiddler with his hands and feet in the most inhuman manner.
“Such gross indignities my worthy grand-uncle was not accustomed to, and being incensed beyond all measure at the liberties taken by Bogandoran, he resolved again to try his mettle, whether life or death should be the consequence. Having no other weapon wherewith to defend himself but his biodag, which, considering the nature of his opponent’s constitution, he suspected much would be of little avail to him—I say, in the absence of any other weapon, he sheathed the biodag three times in the ghost of Bogandoran’s body. And what was the consequence? Why, to the great astonishment of my courageous forefather, the ghost fell down cold dead at his feet, and was never more seen or heard of.”