to get the achievement for the 60+ armor gain armor with high protection rating base, then add armor that has additional protection properties and upgrade your mysticism skill. This will increase the maximum additional protection you can add
If you have complained about finding resources then you should probably go through all of the tactical missions and also enter the dungeon of mystery, because there is an abundance of resources while traveling lower
during defense quest the to hit is all that really matters so wish defense could level up your weapon attack to increase hit ratio and help with dungeons