[Source] Darth Revan's robes were aptly named for being the usual wear of Revan during his time as a Sith Lord, though they were destroyed when he was captured by the Jedi Order, as the Jedi viewed his clothing as an abomination. The robes are created by a mystical technology of the Star Forge in a way to fuel the dark side energies of the wearer through the garments to strengthen him. The Jedi Council, as well as mind-wiped Revan, were unaware that such an item of terrible power could be possibly created by the Star Forge for the second time.