Found randomly in loot containers.
Lost Wonders of the Ages Vol. 3
Disclaimer: This book, like all others in this series, is purely speculation. It will not lead you straight to these artifacts, but it may give an adventurous treasure hunter a leg up. Though it may sound that I have gleamed the exact whereabouts of each relic, these descriptions herald from tales and lore and only relay the clues I have learned.
The Crusader's Relics, the arms and armor of Pelinal Whitestrake, used in his battle with Umaril the Unfeathered, are unique among the various wonders covered in this series. Why, you ask? Because they have been lost not once, not twice, but three times. They were lost the first time following the death of Pelinal after his battle with Umaril. They were then gathered once more by the Knights of the Nine after they were founded by Sir Amiel in 3E 111. They were lost again after the Knights disbanded following the War of the Red Diamond.
The Relics were collected again by the Second Divine Crusader in order to fight Umaril once more when he was reborn in 3E 433. The Relics remained in the possession of the reestablished Knights of the Nine until the battle of the White-Gold Tower, where the current Champion of the Knights at the time, Dame Noriel, fell in battle with the Thalmor.
The remaining Knights of the Nine managed to recover the Crusader's Relics from the battlefield before the Thalmor could get to them. Knowing the Thalmor sought to destroy the Relics as they represented a Divine endorsement of Mankind, they decided to hide them from the Thalmor by taking the Relics deeper into the Empire. The Knights left a garrison at the Priory of the Nine, knowing the Thalmor would come for the relics, while they also sent a force north to Skyrim, hoping to divide the Thalmor agents who perused them. From amongst this group they chose seven knights to safekeep and hide the Relics throughout Skyrim. Each knight was given a chest, crafted and blessed in the name of one of the Divines, that could only be opened by one blessed by that Divine, or the steward of the order themselves, bearer of the ring of Sir Amiel; founder of the order. The ring, it is said, was lost during the Thalmor's efforts to purge the knights and the memory of Pelinal Whitestrake and his legacy by hunting down the members meant to safeguard the chests. All that is known is he was awaiting his brothers somewhere along the far north.
The seven departed from the main force one night, taking the relics where they saw fit. Herein is contained all accounts I have uncovered about the likely whereabouts of the chests and their contents.
The bearer of the Sword was perhaps the most faithful, taking the Relic to the Temple of the Divines in Solitude where all the Divines are worshipped, waiting for a wielder who understands the power of life and death. This chest is the only one of its brethren of which its whereabouts are known for certain.
The Shield of the Crusader could only be claimed by one blessed with wisdom, though the bearer chose to hide it not among those wise in the workings of the world, but in the cellar of one wise in the knowledge of passing travelers. I can only surmise that the chest must be tucked away within an inn or hostel of some sort.
The bearer of the Boots hid them near a fort once owned by an order dedicated to the eradication of the unnatural. They rest among native animals, waiting to be claimed by one blessed with an appreciation of nature. So much is considered unnatural to the Nords that the legendary whereabouts of this chest could almost literally be anywhere; from a dark Falmer infested Dwemer ruin to a dormitory room of the Winterhold Mage's College.
The Helm's bearer had less luck than the others. She was nearly caught by wandering Thalmor in her travels and forced to flee further north. She slipped their pursuit near a fort in the Pale, taking the Helm underground in a nearby cave. The Helm now languishes among the hideous cavern-dwellers while it waits for a champion of Beauty to recover it. Again, mentions of the hideous immediately draw my thoughts to that of the Falmer or perhaps Hagravens of Skyrim, but any who seek to find it would do best to start searching the areas around ruined forts in the northern Pale for nearby caves.
The Armor of the Crusader awaits a champion of the age, blessed by time, to recover it from the cave in which it rests, northeast of a town of stone. The passages concerning this legend are vexing to me to be certain. While some accounts imply that the blessing of the chest was imparted by Mara, others imply that it was Akatosh himself, which leads me to believe that the Greaves and Cuirass may well be safeguarded together within the chest. As we well know through the legends of the Crusader's relics, each of the original Eight Divines bestowed a relic, and yet there are only seven chests according to all sources concerning the chests. I would hate to think that one of the chests containing the Armor or Greaves has been lost to all time. As for the location, I would only surmise that the Reach is what is being spoken of, but the entire area is littered with spires from Dwarven ruins, so the exact location would be very hard to determine.
The bearer of the Mace brought it to a fort at the crossroads of several holds, to be found by one who knows the value of honest work. An elusive legend to be sure and providing only a vague insight as to the location it speaks. There are several crossroads throughout Skyrim, but the most likely perhaps would be one of the three crossroads that surround Whiterun, the central most hold in the province.
The bearer of the Gauntlets believed himself a crusader in his own right, and ended up chasing a vampire through the Reach after a failed attempt to execute it. He chased the vampire into a tomb, blinded by rage and slew them. He then realized he had run through a home of the dragon cults of old, and sealed away the Gauntlets before facing the undead horde he'd awakened. Hoping someone more merciful than he would claim them, he fought to his last in repentance for his failure.