In the Mortal Dynasty, silk symbolized status and rank, and it was the same for Cultivators.
Those who could wear Vestment robes were invariably Inner Sect disciples of a Major Sect or Great Cultivators with a Golden Core. And even among Vestment robes, there were different grades, with the highest being called the Purple Ribbon Immortal Robe, created by a great power incorporating their own Daoist Skill, forming a manifestation of the Great Tao.
Those who often possessed an Immortal Robe were usually the founder of a sect or a Demi Immortal giant.
One could be a Demi Immortal without a Purple Ribbon Immortal Robe, but having one definitely indicated one was a Demi Immortal.
This is what Yu Hua once told him, and she prepared a Golden Silk Feather Robe for him, which was one level below the Purple Ribbon Immortal Robe, the highest-level Daoist robe of the Sanqing Taoist Sect.