The explaination that Art is giving is good. The "Garment" symbolically represents the prophethood, and the revealer of the Word of God.
It comes from the story of Joseph the Prophet. The Bab has already revealed the meaning of it in Qayyumu'l-Asma.
When the Garment of Joseph was placed on the eyes, it healed them. Meaning, the word of God gives spiritual healing, and opens the eye, so the truth can be seen.
Here is a tafseer:
"
On Joseph's garment:
"Say: From My laws the sweet-smelling savour of My garment can be smelled. . . "
(Aqdas, paragraph 4)
As the House of Justice has pointed out in the Note for this paragraph (Aqdas, p. 165), the Writings state that the fragrant garment is a metaphor for recognition of the Manifestation. See how clearly this matches the description in the New Testament, and unseals the metaphor being presented in the Gospel:
"And when the men of that place recognized Him, they sent out into all that surrounding region, brought to Him all who were sick; and begged Him that they might only touch the hem of His garment. And as many as touched it were made perfectly well." (Matthew 14:35)
"And behold, a woman who had a flow of blood fo twelve years came from behind and touched the hem of His garment; for she said to herself, 'If only I may touch His garment, I shall be made well.' But Jesus turned around, and when He saw her He said, 'Be of good cheer, daughter; your faith has made you well.'" (Matthew 9:20)
In the Old Testament history, the metaphor of the garment of the Prophet protecting the people from drowning, and enabling them to walk on dry land to the far shore, is found:
"Now Elijah took his mantle, rolled it up, and struck the water; and it was divided this way and that, so that the two of them crossed over on dry ground." (II Kings 2:8)
As Bahá'u'lláh says in the Seven Valleys, p. 9, the knower is "dry in the sea."
Here, the Revelation of Bahá'u'lláh is foreshadowed in prophecy:
"I watched till thrones were put in place, and the Ancient of Days was seated; His garment was white as snow, and the hair of His head was like pure wool.... Then to Him was given dominion and glory and a kingdom, that all peoples, nations, and languages should serve Him. His dominion is an everlasting dominion, which shall not pass away, and His kingdom the one which shall not be destroyed." (Daniel 7:9)
Christians understand the following verse to mean that Jesus merely renewing the Jewish Revelation would not have been adequate. Both Revelations are spoken of as "garments":
"No one puts a piece of unshrunk cloth on an old garment; for the patch pulls away from the garment, and the tear is made worse." (Jesus Christ, Gospel of Matthew 9:16)
It is possible that as early as the first night of this Dispensation, in the opening verses of the Qayyumu'l-Asma, the Báb may have unsealed this metaphor for Mullá Husayn. It says in the Súrih of Joseph (and in the story of Joseph in the Book of Genesis) that when the brothers of Joseph entered His presence they did not recognize Him; later they recognized Him, meaning that men do not at first recognize the Manifestation, and later they do. When the brothers of Joseph returned to Egypt to tell their father Jacob that Joseph was alive, they had brought His shirt and cast it on Jacob's face. He recognized the scent of Joseph, again a symbol for recognition of the Manifestation. This verse (Qur'an 12:93) is the origin of this metaphor in the Aqdas. It is also interesting that Jacob "remembers" the scent of Joseph, and the "remembrance" of God, in the sense of the Mashriqu'l-Adkar, the Dawning-Place of the Remembrance of God, is related to this."
Qayyúm al-asmá: Faculty notes