Mechanomancers
A Mechanomancer is a Zarth who uses magic to create and power mechanical devices. Mechanomancers should be able to exert their own life energy as well as pouring their power into their craft. Zarth magic relies on sacrifice, whether self sacrifice, or the sacrifice of others. This makes the "magic" of the Zarth much more mechanical, and focused, than that of the fay.
Mechanomancers can convert magical energy to mechanical force, or vice-versa. Thus, most Mechanomancers carry tightly wound springs to fuel their spells. Most squads in the Regiments carry at least one Mechanomancer to allow their soldiers to use magic without becoming exhausted or reducing their lifespan.
Mechanomancers also craft mechanical devices such as weapons, mining tools, vehicles, and energines. They are engineers of a sort.
Other ideas
Tribal magic, a whole tribe sacrificing to power one Zarth's magic?
Drawing on sacrifice along the lines of the Regiments?
Masculine power traits:
Focused
Instantanious
Single target