To be blunt, this was the pinnacle performance of a weapon custom made by individuals. Mass-produced rune weapons were normal weapons that were able to conduct soul power. For customized rune weapons, they were made to be compatible with the specific wielder's soul power frequency. This allowed for greater exerted power.
Professor Moore was an outstanding figure among the Federation's current generation. Yet, the rune weapons produced now couldn't reach the same standard as their dark era counterparts. Some said this was due to the loss of certain technologies, while others said it was due to a change in hyperdimension energy.
There were many confusing and diverse theories, yet every rune grandmaster placed those old weapons as their target. The reason why those weapons were so well-known across the world wasn't due to their wielders, but their creators.