Sauron may not be the greatest Dark Lord in the world of The Lord of the Rings, but by the Third Age, he was the ultimate source of darkness. Accordingly, when his power began to grow for the second time, Sauron drew to himself all of the evil things in Middle-earth -- among them, Orcs, Saruman the White and a Black Númenórean known as the Mouth of Sauron. However, his greatest servant was none other than the Witch-king of Angmar, leader of the Nazgûl.
Peter Jackson's film adaptations depicted the Witch-king as a formidable foe. However, the director left out a key detail from his death at the hand of Éowyn. In J.R.R. Tolkien's novel, The Return of the King, the Shieldmaiden of Rohan was only able to kill the Witch-king because of a magic sword. Here's why Jackson left out that detail.
How Was Éowyn Able to Kill the Witch-King?
The moment arrives near the end of The Return of the King, as the Battle of the Pelennor Fields rages. As King Theoden lay trapped under his horse, mortally wounded, the Witch-king tells his Fellbeast to "feast on his flesh." Out of nowhere, one of the Rohirrim steps up to defend the Lord of the Mark, only for the Witch-king to proclaim, "You fool. No man can kill me."
Every Lord of the Rings fan knows what happens next: The two engage in a shield-splintering fight, and the warrior is nearly killed. Nevertheless, the Hobbit Merry Brandybuck stabs the Witch-king in the back of the leg. That allows the warrior to reveal herself as Theoden's niece, Éowyn, who declares, "I am no man!" before plunging her sword into the dark depths of the Witch-king's helmet. However, there is a little more to the story, and it involves a magic sword. However, It wasn't Éowyn's blade that was magically imbued; it was Merry's.
To understand that point, Lord of the Rings fans have to turn to The Fellowship of the Ring novel. At the beginning of the book, Frodo and his three Hobbit companions encountered the legendary Tom Bombadil, a character cut from Jackson's adaptations. Omitting Bombadil is a debate for a different article. However, in choosing to do so, Jackson was also forced to remove the Hobbit's near-deadly encounter with the spirits in the Barrow-downs.
Éowyn's Battle With the Witch King Differed in the Book
After Tom Bombadil rescued the Hobbits from the Barrow-weights, he gave them daggers that were hidden within the burial mound. Those weapons were of special significance because they originated in Westernesse, also known as the Isle of Númenor. Forged by the smiths of Arthedain, the daggers were intended for use in the war between Arnor and Angmar. As such, they were enchanted with magic capable of harming the Witch-king.
Of course, in Jackson's films, the Hobbits' daggers were of no real significance because they didn't come from Tom Bombadil or the Barrow-downs. But in Tolkien's book, the magic weapon made a huge difference. So, when Merry stabbed the Witch-king in the source material, he didn't merely distract the Lord of the Nazgûl. Instead, he dealt a great blow by breaking the spell that made the Witch-king near-immortal. To wit: Merry's blade broke "the spell that knit [the Witch-king's] unseen sinews to his will."
Essentially, Merry's magic dagger opened the door for Éowyn to kill the Witch-king. That, however, doesn't diminish her big moment. It means that it wasn't her femininity that permitted her to kill the Witch-king; it was her will. Anyone could have killed the Nazgûl after Merry weakened him, but only Éowyn had the courage to defend her king against him.