What is the Medici Dagger?
After spending some time researching your question, I have found that there is a book by Cameron West entitled The Medici Dagger. It tells the story of Leonardo Da Vinci's creation of the Medici Dagger 500 years ago. According to the book, he invented the dagger using an alloy that was both lighter and stronger than anything else known to mankind. Once invented, Da Vinci realizes that the dagger will be used for evil. So he hides it and encodes a map called the Circles of Truth for future generations to find it. In the book a Hollywood stuntman sets out on a journey to find the dagger, before a billionaire munitions dealer gets his hands on it. The book is sold as "fiction", so I am assuming that this was a fun follow-up to Dan Brown's book The Davinci Code which has become one of the most widely read books of all time.