The Bodhisattva said:

菩薩道 — two characters of speech-attribution, and then the longest set-piece in the chapter.

This cassock — let a dragon drape but one thread of it, and it is spared the disaster of the roc's devouring;

Note how the cassock is introduced: not by what it is but by what it keeps off. One thread of it laid on a dragon saves the dragon from the 大鵬, the roc, which in Buddhist legend preys on dragons.

let a crane hang but one strand, and it gains the marvel of passing beyond the mortal into the holy.

得 in 得超凡, gains the marvel of passing beyond the mortal, is dé, to attain.

Wherever its wearer but sits, ten thousand spirits pay court-homage;

朝 in 朝禮, to pay court-homage, is cháo — ten thousand spirits queueing as officials do.

in his every movement, the Seven Buddhas attend him.

The 七佛 are the Seven Buddhas of the past, of whom Sakyamuni is the last.

This cassock is spun from the silk of ice-silkworms, drawn into thread by cunning artisans, tossed and worked into yarn, woven by immortal maidens and finished on the loom by goddesses; square upon square, its panels gathered and sewn with embroidered flowers.

The 冰蠶, ice-silkworm, is a legendary creature that spins silk in the cold. 為 in 翻騰為線, tossed and worked into thread, is wéi, to become or be made into.

Piece joined to piece, heaped upon the brocade reed.

相 in 相幫, joined to one another, is xiāng; a 簆 (kòu) is the reed of a loom, the comb that beats each thread into place.

Exquisite scattered fragments vie in their flowered adornment; bright of hue, drifting light, spurting jeweled splendor.

散 in 散碎, scattered, in fragments, is sǎn.

Put on, a red mist wreathes the whole body; taken off, a swath of colored cloud takes flight.

The couplet balances putting on against taking off, and gives each its own weather: red mist wound about the body, a stretch of coloured cloud in flight.

Beyond the Three Heavens' gate it lets through a primal radiance; before the Five Sacred Peaks it breeds a jeweled vapor.

The 五岳 are the Five Sacred Peaks of China; the 三天 are the Daoist Three Heavens. A Buddhist robe is being measured against Daoist geography, and quite deliberately.

Layer upon layer inlaid with Western lotus-blooms; glittering, hung with pearls in the images of the stars.

重重, layer upon layer, reads 重 as chóng; 斗 in 星斗, the stars, is dǒu. 西番蓮 is the passionflower, or Western lotus, as a decorative motif.

At its four corners are night-shining pearls; gathered at its crown, a single emerald.

祖母綠 (zǔ mǔ lǜ) is the emerald — three characters that read literally as 'grandmother green,' the word being a borrowing and the grandmother an accident of sound.

Though it does not wholly reveal its original substance, yet it has the radiance of eight gathered treasures.

攢 is cuán, to cluster or gather in, not the zǎn of hoarding up. The 雖無 … 也有 construction closes the inventory in the oldest rhetorical way there is: concede a limit, then override it.