Fanaticism can be just as dangerous as fire. Spreading like fire, it could spark rebellion and could lead towards violence. As a way to curb devotion to the abstract, king Hareth of Garilroot asked his Mages to come up with a solution for those too invested in an ideal.
Swordbiters are parasites. They are long, thin and silver, and digest metal, somewhat like rust monsters, but smaller and more insidious. They resemble stick insects, but when they cling to metal they are very well camouflaged, and one can be biting your sword for a week before you notice it. They cannot be removed by hand, as they are very strong, but if the blade is inserted into fire they will leap off to escape the flames. Sometimes, old treasure hoards are infested with them, and the first glimpse you get of the "glittering" weapons is a pile of rusted swords encrusted with these thin silvery insects.