This clue may have been hidden by Fidelio Racco, Wolfgang Amadeus Mozart, Maria Anna Mozart, and Marie Antoinette. Marie Antoinette is famous for the saying, "Let them eat cake!". The French word for cake is gateau. Taking the letters away that form the musical scale leaves only t and u. TU is the old chemical symbol for tungsten, which is now known as wolfram. On the gate of Fidelio Racco's mansion is a wolf and a ram, forming wolfram.
Tungsten is a metal which actually has the highest melting point of any other metal. It is commonly used in Japanese Samurai swords.