"Oh, this?"  She held up the glass sword.  "Yep, you're right, it is made of glass.  Chiaroscuran glass, to be specific.  See, there's this story..."  Merame painted Yifa a picture, telling her about Chiaroscuro during the height of the First Age, how the Solar Exalted had made the Old City out of magically crafted and enhanced glass.  About the destruction of those mighty glass towers after the Usurpation.  And more.<br/><br/>"You see, someone discovered that Chiaroscuran glass, while broken, still retains its magical strengthening.  And so, using grinding techniques, and large enough shards of glass, it's possible to make weapons out of them!"