Noah didn't limit himself to use his dark matter whenever he had the chance. He first tested how much the inheritance allowed him to cheat.
The tests became impossible to overcome whenever Noah tried to use his "Breath" or mental energy, even if he limited them to the simple boost of his physical strength.
The same happened when he deployed the dark world or used the dark matter to create the fiendish armor. The "strength" tower only tested his physical prowess and gave rewards meant for his body. Unless the test expressly said so, he couldn't use his abilities.
However, the inheritance didn't react when he used the dark matter to activate his innate ability. It seemed that the tests saw the dark vessels as an extension of his physical strength, and the same applied to his dark flames, even if they weren't useful most of the time.