Final answer:
Sigurd used a sword made from the broken pieces of Regin's magical sword to kill the dragon guarding Andvari's gold.
Step-by-step explanation:
The correct answer is a sword made from the broken pieces of Regin's magical sword.
In Norse mythology, Sigurd (also known as Siegfried) used a sword crafted from the broken pieces of Regin's magical sword, Gram, to kill the dragon Fafnir, who was guarding Andvari's gold. Regin was a dwarf who had originally forged the sword, and when it broke, Sigurd reforged it to slay the dragon.
Using a sword made from the broken pieces of someone else's magical sword is a common theme in mythology, symbolizing the hero's ability to overcome challenges and inherit power.
Learn more about Norse mythology