Shi Feiyang was set on obtaining the Nanming Leaving Fire Sword, having calculated all the causality involved very clearly, he should be able to acquire it smoothly.
As for the public case between Dharma Master and Guiyi Monk, he had no worries about it. A magical treasure is akin to a tool; why use hands to eat when there's chopsticks? Why walk on foot when there is a car? Once one is capable of "Can Xia" and "fu qi," chopsticks become unnecessary; once one is able to fly and burrow, cars become redundant.
Guiyi Monk treasured golden chopsticks as if they were precious, even when he could abstain from eating grain, he kept the chopsticks, and then every time he saw them, he felt hungry, and his abstention from grain failed, his realm consequently remaining at an impasse, unable to reach perfection. There were no demon barriers, but he created his own barriers, his own demons, and he wasted nineteen years before he finally came to understand this principle.