For clarification:
This alloy has more uses than just "another anti spook weapon". This alloy is easily enchantable, which allows it to be applied to (as Cablam previously state) Arcanic items/Arcane engineering, and even more non-magical affairs (see Magnetus).
While it is able to harm spooks, keep in mind that this alloy requires a lot of time and effort to make (not to mention the process of actually discovering it. Good luck to anyone who is going to pursue that venture), not to mention the danger of improperly handling Arcanium (Breaking it making quite the hectic situation).