It is generally agreed upon by historians that it was indeed the ancient Abassan empire that first discovered the practical applications of Nivium, but cultures all over Myr had been collecting the material merely because of its rarity and beauty, a deep religious connection to the material has always been present, as with gold and silver.
The first to discover its applications were of course the first to use them to destroy their enemies, The first Stormriders out of Abassi did not have concrete understanding of how their new powers worked. They only knew that after exposing themselves to the elements, say strong wind currents or a hot sun for an extended period of time, the elements would seemingly have an affect on any Nivium enameled jewelry/clothing they had and that they could release this power in the form of powerful wind currents. It took some time, but offensive uses of these powers soon became the most important aspect of the Abassan empire's military. Sometimes Strormriders would set out and teach new communities how to mine for the metal and even provide reward them for their contributions.
Nivium enhanced sharpshooters of the Abassan empire could use their power of the wind to ensure every arrow they fired not only hit its target, but also punctured faster and deeper than anything until the invention of gunpowder.
Cultures around the globe attempted to imitate this mastery over what seemed like magic, but learned that it is practically impossible to learn the skill without tuition by a master himself.
Independent of the early southern Mancery the Harkonians stumbled upon a different kind of Nivium usage, instead of temporarily harnessing the power of nature and releasing it, they learned to drain the energy from the environment itself, the only time they needed to 'use' the energy was in battle when it was necessary to rapidly freeze and opponent. These masters of nivium became known as Iceweavers.