User blog comment:Alchimous/Mithril is.../@comment-1510327-20130227224015/@comment-24180511-20130227225124

You're thinking about it backwards, mithril is stronger than steel. All that means is there are things stronger than mithril. Dragon metal uses crystalline molecular bonds(from a postbag), which give it it's strength. There are things stronger than titanium, there are things stronger than mithril.

In any fantasy setting, it's easy to have something harder, or stronger. You just need to see if it closely mirrors the real world counter part, which in this case it does.