Board Thread:Skyrim/@comment-108.238.224.19-20130331211734/@comment-62.255.144.96-20130331232547

the blackguard's armor is part of the dragonborn dlc, in the first town you visit in solsteim he is the blacksmith, do his two missions and he will give you the keys to his house and secret room in the baasement, where the armor is located, along with some loot and thieving potions. Hope I helped :D