Kabbalah su Salmi 104:2

And he smelled the smell of his garments, and blessed him" (Beresheet 27:27). Come and behold, It is not written, "and he smelled the smell of the garments" but "the smell of his garments." This is according to the verse, "Who covers Himself with light as with a garment, who stretches out the heavens like a curtain" (Tehilim 104:2). Another explanation is that once Jacob wore them, they emitted an aroma. As long as Isaac did not smell the aroma of the garments, he did not bless him. But then, he knew that the wearer was worthy of being blessed. For if he did not deserve to be blessed, no holy aroma would be put forth. This is the meaning of the verse "and he smelled the smell of his garments, and blessed him."

When Moses was taken before Pharaoh, God took it from him, and did not give it again until he stood upon the mount of Sinai to receive the Torah. Thenceforth Moses had it for his until the end of his life, and therefore he could not be approached by the Israelites until he had put a veil upon his face {Exod. 34:33}.