Oh, right. Considering Elsa had never heard of Amestris before, Ed isn't surprised that automail is foreign to her.

"It's called automail. It's a common prosthetic in Amestris." He sighed. His point about the dangers of human transmutation being dulled by the fact that he assumed Elsa knew of something she had no reason to. "My brother and I tried it once. It didn't end well." It was usually Al who filled in the blanks. Neither he nor Ed were too shy about what they had done, so long as it wasn't around any military personnel who could court martial Ed for it. They'd rather people know of the consequences then be pushed to believe that it was something they could pull off.