The various pieces of Mythril Armor are very nice, in that they have the same weight (and magic penalty) as the Bronze Armor you've likely been using, but provide a lot more defense. They are also the first armor pieces you're likely to find that provide a bonus to magic defense. You will want to pick up the Mythril Armor when it becomes available, because you won't find another suit for quite some time, and it's a nice boost to defense. If you're not a fan of heavy Armor, keep in mind that the cheaper Silver Cuirass available in Bafsk has the same defensive properties.