From Silver Sun Republic Codex

Historically officers of the Ministry of Commerce who deal in collecting and assessing taxes, rent, fees and enforce civil economic law. They also handle the process to license artisan companies. Additionally they negotiate and fulfill contracts on behalf of the government.

For Life is Feudal, officers were spread throughout each of the Ministries and not tied to any one specific Ministry. This meant that Commerciantes applied their focus on fee collection and logistics to the other Ministries of the Republic. Commerciantes in the Ministry War operate as Quartermasters.