Finally got around to testing Barrier status. It turns out that the Tower of Bab-il documents were right (mostly): when you have Barrier status all physical attacks that target you fail (i.e. they miss). This includes Jump and Power, which also miss. Throw, Kick, and DarkWave can still do damage.
The status effect also never faded. Hitting the target with magic damage or curing the target also didn't remove the status. Does the Lunar Curtain work this way? The strength (or duration) of it is 14. I cast a spell that put Barrier status on with a strength of 0A, so the Lunar Curtain should last even longer. The thing is, if it doesn't fade for most or all of a battle, it seems like a pretty unfair advantage to give a character. How rare was the Lunar Curtain in the original game? It seems like it would have been extremely rare given its usefulness.