Revolute

Revolute was a sword used in legends by Aren of Arendelle and by Elsa in a fight against the Nattmara. It is a crescent blade made of an unusual, blue-black metal and there is a yellow diamond in its pommel.

History
Revolute was hidden inside the dragon sculpture in Aren's tumulus. Anna took it out and ran outside to face the Nattmara, but Elsa took the sword from her, closed Anna in an ice shelter and went to fight with the wolf. During the fight the blade shattered.

Legends
According to saga of Aren, the sun gave the sword to Aren impressed by his deeds. Aren used the sword to carve the Arenfjord and later to defeat many mythical beasts.

Trivia

 * 'Revolute' means 'curved'.
 * 'Revolute' is an anagram of 'true love'.