You can vanish past the bronze nonsense. It works perfectly. In fact, I am never using Dragon Plate Mail in my games ...
If you do not want to vanish then you
must have the mail equipped by someone of your party. Otherwise, you will meet the barrier you have spoken about. Note that having high Fire Resistance or having a custom made equivalent of the mail does not help - you must have the right Dragon Plate Mail.
Therefore, a solo omphaaz must vanish past the bronze nonsense. All other classes and races can wear Dragon Plate Mail.