Often principles such as 'like calls to like' are used to explain Grisha power, and most Grisha see their 
 powers as "extensions" of the natural world which is why they don't call their power "magic" but instead Small Science.  For example, Inferni cannot produce fire but can manipulate naturally occurring combustible gases, and Durasts do not create metal: rather, they simply have the ability to alter it. 

This is basically what grisha are soldiers who can have those abilities and where something called a kefta which is 

A kefta is a garment that is worn by Grisha in the Ravkan Second Army. The color of a Grisha's kefta is determined by their Grisha order, and the color of the embroidery on the cuffs and hems signifies the wearer’s specific abilities, or their Grisha type within the order.

Kefta are described as long, nearly-floor-length robes that somewhat resemble coats. The garment consists of several panels of fabric and is secured with hidden buttons on the wearer’s front.