"Bullion," when referring to epaulettes, means a heavy twisted fringe
of cords, but the word obviously has a second meaning relating to the precious
metal that Don Pepe is in charge of mining. The epaulettes' "tarnished"
quality intimates that we're to imagine silver bullion, not gold, but also carries
a moral meaning. See Mrs Gould, whose prosperity can only be kept "without
a stain" on its "immaterial side."
We are on the decidedly material side of the dream-ideal here, where its implementation
requires "a great sword," and sure enough, we find the "stain."