Looking good! A simple and effective addition to the original game (by the way, thank you for giving me the reason to re-visit Verge!). Can you add a few examples of True Magic in action?
Hmmm.... being of the natural world, I had thought that it would lean toward the healing end of things, as well as having some elemental possibilities. Probably things in the earth and water elemental realm as well as having some bearing on interacting with the spirits in a more cooperative manner.
Cold Iron on the other hand, I feel would lean toward offensive uses in the air and (paradoxically) fire elemental ranges due to my thought that it would be connected to the burning of the forest. I thought it would also be nice to have a little overlap in the spirit realm, but that Cold Iron would be more compulsory in how it interacts with the spirits.
Does that give enough general feel there? I admit that I hadn't thought too deeply into specific examples, but I should at the least work up the above descriptions a little more to fit in.