a sharpening 'steel' [=a steel rod that has a rough surface and is used for sharpening knives]
He had a grip 'of steel'. = He had a grip 'like steel'. [=he had a very powerful grip]
She came from a 'steel town' [=a town where steel is made] in Pennsylvania.
(..) and here I sit hosting one in my hall thanks to my son. See that sword? It's called Heartsbane. It's been in our family for years. It's Valyrian steel. Only a handful of them left in the world. It's supposed to go to my firstborn son after I die. To him. (..)2016 TvShow: Game of Thrones Title: Blood of My Blood Season: 6 Episode 6