The Shadow Wielder and the five Elements

Welders are people, who are born with a special power. The rarest ones are elemental welders. People ,who can world the elements at will are considered special and unique. There are five main elements and one forbidden one. The main ones are water, fire, earth, wind, and light. There are only five born each a century before the next generation. But there is also a forbidden element, the shadow. When a welder is born with this element it is quickly taken away and locked in a cage, until it dies and just like the main elements it takes a century until another is born into the world. While the main elements are treated like Prince or princess, the shadow welder is treated like a slave.