Over the course of long years, they excavated a great deal of the Nation of Magical Machinery's technology and put it to use, bestowing a new name upon pure gold attribute Beastmasters-- Mechanics!
Mechanics, by creating mechanical constructions and engendering Mech Souls, drastically reduce the chances of abnormality. Even if their machines are tainted, unlike blood and flesh organisms, they can be repaired by replacing components, demonstrating much stronger vitality!
The only drawback is, probably, money!
Not only does one need to be rich, but they also need to be self-sufficient financially!
With the spread of mechanical technology, the formerly poor and perilous Holy Gold Domain underwent a transformation, becoming a land of golden hills and silver mountains. The ferocious metal demons all became raw materials for high-grade machinery in the eyes of the Mechanics, making it possible to manufacture machines with local materials.