How Did Éowyn Slay the Witch King of Angmar if He Wasn't Alive?
In Lord of the Rings: The Fellowship of the Ring, Aragorn, as Strider, tells the four Hobbits about the Nazgûl, and describes them as "neither living nor dead." Gollum later tells Sam and Frodo while they're trekking through the Dead Marshes that the Nazgûl cannot be killed. Yet, during the battle at Minas Tirith, Éowyn simply stabs the Witch King of Angmar in the face with her sword and he ceases to be.
How could Éowyn have slain the Witch King of Angmar if he wasn't alive to begin with, and was supposedly unable to be killed, as he was caught between life and death in some kind of Nazgûl-ish limbo? How did she destroy him?
"How do you kill that which has no life?" - Blizzard Exec #4 from South Park's Make Love Not Warcraft.
This was much better explained in the books. Merry had picked up his sword (actually a dagger, but he's a Hobbit so it was size-appropriate) in the Barrow-downs near the Shire. (The entire Barrow-downs part of Fellowship was removed for the film -- it took place between the Hobbits' first encounter with the Nazgûl on horseback and their arrival in Bree.) The dagger had originally been forged in Westernesse, for the specific purpose of fighting the forces of evil:
"Doubtless the Orcs despoiled them, but feared to keep the knives, knowing them for what they are: work of Westernesse, wound about with spells for the bane of Mordor." - Aragorn
Additionally, this FAQ entry quotes Gandalf in an early draft of LotR describing them as "the one kind of sword the Riders fear." And this one contains some discussion about who actually killed the Witch King -- Merry or Éowyn?
The LotR wiki article says Merry's sword was actually made in Westernesse (Númenor) before its downfall.
Nice answer! Thanks for not just quoting the Wiki at me -- I appreciate the extra effort. +1