@Questor question: does orichalchum interferes with gryphon's flight (That should be at least partly magical after all), or with Yaks/Oni/Troll magically enhanced strenght, or does it only interferes with "active" magic? Does it work on magical plants (assuming we have any of those to experiment on)? Does it dispel Kitsune's illusions? Can gwin still breath fire if she's holding the metal?
We need to understand what exactly count as "magic" in regard to the anti-magic quality of the metal.
For the ones we don't know we'd probably need a new series of experiments, but at least the one about blocking flight and fire-breathing are easy to check.
If it needs direct contact (or does not stop flight) then our knights could fight with Oricalchum weapons as long as they're not actually touching the metal blade, you just need to make the hilt of a different material.
So, we have a nice anti-magic metal. Weapons for our more elite warriors are the first thing that comes to mind (royal family, a gift for the emperor, the Grandmaster Knights, the knights of the inner circles and the normal knights (if we have enough))
After that, the second idea is manacles, shackels, handcuffs, hornrings, collars.....basically restraints for the various races.
Depending on how much we have we could make even the gates of our fortresses out of it.
And for hitting/hurting Sombra in gas form/the Windigos we could make some special oricalchum tipped arrows/Ballista projectile, and oricalchum coated cannonballs (no reason to make them COMPLETELY of it if just coating them is enough of a disruption. This must be tested too)