The Writer glimpsed it in his journeys through the various hells, but he paid no heed to it. His tale was about the afterlife and the punishments therein, not the arms and armor of the Darkness.
The grave robber grinned as he left the royal barrow, his pockets full of stolen gold, and dressed in a helmet and chainmail shirt stolen from the now naked, decomposing body of the king. The explosion that followed ten seconds after he stepped into the sunlight wiped the smile from his face and blew his body into pieces. Had he studied metallurgy, he would have known that the armour was made of pure Orthacarium and he would have left it alone, and escaped the barrow with his life.
Arune Spheres are hollow, blue reflective metallic spheres about 25 cm/ 10" in diameter (though some are larger). They are made of a thickish glass mirrored on the inside. When magical energies are flowed through the sphere, it produces a haunting tone, which can be varied by the type, intensity, and harmonics of energies passed through it. (It sounds like an electronic organ.) If multiple energy flows are generated, multiple sounds can be generated, some of which sound like mundane instruments. Masters of The Craft can replicate almost any sound in their memory with one. Though originally used as a training tools for those with The Power, it has been adapted to be a musical instrument. All it takes is someone with patience, medative training, and a touch of the Power, to use it. (Thus becoming the favorite instrument of anyone who was tested to the first level of the Craft, but failed to advance).