The Weaponmancer Civilization was unique due to its magic system.
Generally speaking, most worlds had the same magic system where mages could call upon various elements. And these elements were also largely the same though there would be a few anomalies. For instance, Victoria.
The world Marcus came from was also somewhat unique due to the fact that the mages there had the usual elemental magic, but they all had a touch of darkness to them.
Now in the case of the Weaponmancers, they considered elemental magic as merely a sub-branch of their whole magic system as each and every weapon an individual was born with was unique. They could be similar, but never quite the same.
You could have a weapon which allowed you to manipulate multiple elements, or a weapon that allowed you to cast mental attacks, or be something similar to a necromancer, and so on.