So I noticed that most items say things like-
"Combining the principles of the Skylark's engines with the technology powering the Blast Furnace produced this brutal blade, which can ignite even the most flame-retardant materials at a distance. "
And are then sold in the hall of heroes. This would mean that the Spiral Order has researched the blast furnace, and then created the technology for combuster. In other occasions, the technology comes from gremlins, and then uses the Spiral Order's technology... these items are only created for the spiral order's highest people, and thus are not sold in the Hall of Heroes-
"A cutting-edge handgun intended for use only by the Spiral Order's best and brightest. Pulsar shots become more powerful the further they travel. "
And then there are other items that were created by monsters, like Triglav, and are only sold by krogmo, and still other items like divine avenger that entirely came from somewhere else.... these must have been found as recipes by the strangers, and are still a secret to the spiral order. Amongst these however, is the graviton vortex. The gremlins obviously either researched it and mimicked it with the electron vortex which krogmo must have found.
But the graviton vortex is different from the sealed sword and other items in that it doesn't come from anywhere. Theoretically, the sealed sword/antigua must have been found in the clockworks by the spiral order.... who then wanted to give them out to knights.
There were no original graviton bombs left that the spiral order has found to our knowledge, and there are no enemies left capable of using them, which means that either the graviton recipe came in when cradle was formed, or that the graviton recipe came in with a civilization that has fallen.
I thought it was just techno-babble.