Yeah, as others have said, if you can't equip an item as the class you currently are, glamours will not appear. (Which makes me sad because I want that PvP bard coat, but I'm nowhere -near- the rank requirement... so I can't even glamour it...) Incidentally this leads to some interesting setups; I currently have my Daystar Robe (WHM/SCH) glamoured with an Augmented Scholar's Coat. So if I equip it as a SCH, I see my AF coat (dyed in a lovely Ixali blue). If I equip it as a white mage, however, instead I see the Daystar Robe, colored in the same color as the "missing" glamour.

So unfortunately if you want that sword, you're gonna have to join up with the Adders. At present there's no way around it.