On Zetacron, the nature goddess Gaia did not create the elves, but wished to claim them as Her own (it seemed fitting to her, somehow, that elves should be bound to Nature). Thus, she used her divine powers to create a bond between Herself and the elves.
Context: The gods of Zetacron are physically present in the world. You can go and meet them if you like. Additionally, they are very human, with flaws and quirks—possibly more than regular people.
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.