There isn't any metaphors in this song, This is about the book 'the Hobbit', Smaug the Dragon of Erebor to be exact.
"My armour is like tenfold shields, my teeth are swords, my claws spears, the shock of my tail a thunderbolt, my wings a hurricane, and my breath death!" Smaug's description of himself, from The Hobbit part 12, Inside Information.
There isn't any metaphors in this song, This is about the book 'the Hobbit', Smaug the Dragon of Erebor to be exact.
"My armour is like tenfold shields, my teeth are swords, my claws spears, the shock of my tail a thunderbolt, my wings a hurricane, and my breath death!" Smaug's description of himself, from The Hobbit part 12, Inside Information.