Which of the 140 historical royal ceremonial objects known as The Crown Jewels of the United Kingdom is known as the Sword of Mercy? 
Curtana: Curtana, also known as the Sword of Mercy, is a ceremonial sword used at the coronation of British kings and queens. Curtana:  One of the Crown Jewels of the United Kingdom, its end is blunt and squared, said to symbolise mercy.
i don't know