It is supposed to be a physical process, like some materials glow when struck by UV light, so it is difficult to interfere with it apart from blocking the magic emmissions.
Now, since it is not in itself magic, spells could be created to darken the material again or otherwise hide it's feedback. Without any magical energy of it's own, it will have no way to oppose a magical effect.
As for it's mechanical strength, it is an analog to silver and can be mixed with steel or other alloys, but it will reduce the strength of that material. It is much better used as a surface treatment, just as you would silver a sword or arrow. I'm partial to the idea of inlaid runes myself, glowing mystical symbols instead of the whole blade.
In worlds where this metal can be found, use of it to produce devices 'certified' against magical influence would be common. To prevent magical tampering with scales used by merchants, it may be mandated that scales be made or at least coated with such a metal. This of course does not prevent more mundane forms of tampering, but should prevent use of invisable weights. Go to Comment
222. A wooden figurine of a warrior wearing chainmail and armed with sword and shield. 2" tall, it is a child's toy.
223. Wrapped in leather is a large, crystal clear crystal. It is actually an unusually clear piece of rocksalt and worth no more then normal salt.
224. A very crudely wrought key, cut from some sheet metal. It is a copy of a real key.
225. A common to orcish phrasebook, but all of the entries are dangerously wrong.
226. A candle stub, possibly magical (There is about 5 minutes burn time remaining).
227. A pouch of dried crickets (A little known snackfood in these parts...)
228. An oddly shaped 2 oz blob of lead.
229. Handle from a broken teacup.
230. Odd incense that smells of dead fish when burned. Go to Comment