Sintesium
Ancients were covered in a matte white armour that contributed greatly to their silhouette. This material, called sintesium, was commonly found across Core. It was a unique substance that combined properties from ceramics, metals, and polymers. Highly durable, light, resistant to heat and deformation, this material made the perfect material for Core soldiers' armour & weapons, plating on vehicles, and other things throughout their world.
A limited success in emulation of this material has been successfully achieved by Destrian scientists, although only in miniscule batches and with reduced tenacity. The original version of the material required certain elements not found naturally on Legere, and to further widen the technological gap, the sintesium found in the Ancients' construction was blessed by the Angels, enhancing its durability a thousandfold.
Relative to Fire Iron, sintesium was slightly weaker but significantly lighter, making it still quite useful. Its unique properties (like insulation and other non-metal attributes) set it apart from the strongest metals found in Legere.
The sintesium hides peeled from the Ancients circulated Legere in rare batches. Lord Arbam was known to carry around a war sword fashioned from a sheet of sintesium.