Although the Dark Gold Magic Dragon Armor was only Bacarolet's spare armor, it was still a very powerful magic armor set in this era according to Grand Duke Vidi's introduction. Otherwise, it wouldn't have qualified to be Bacarolet's spare armor.
The most powerful attribute of the Dark Gold Magic Dragon Armor was the Domain Barrier. Domain Worlds could be created and owned only by mages. Even Sanctuary-level Warriors wouldn't be able to create their own Domain Worlds, let alone use their domains to defend themselves like mages. However, the combination of mageweath arrays on the armor gave it Sanctuary-level power, which was the best defense.