Apollyon's Sword (For Warmonger). *It’s Warden’s Aragon blade, Garian hilt, & Magnus guard.
Ayu's Helm & Ornament. (For Kensei).
Daubeny's Sun Symbol. (For Knights).
Dokuja's Helm, Ornament, & Embossing. (For Kensei).
Enemy Knight Ornament (Can be seen on multiple Knights in Chapter 3.5).
Enemy Samurai Ornament (Can be seen on multiple Samurai in Chapter 3.2).
Enemy Seijuro Samurai Ornament (Can be seen on multiple Samurai in Chapter 3.4).
Enemy Viking Ornament (Can be seen on multiple Vikings in Chapter 2.2).
Gudmundr’s Armor & Ornament. (For Warlord).
Helvar’s Arms. (For Berserker).
Holden Cross’ Arms. (For Lawbringer). *I know Gryphon has the “Holden’s Lions” ornament, but it’s not the same.
Kizan’s Ornament. (For Shugoki).
Mercy’s Helm. (For Peacekeeper).
Momiji’s Helm. (For Nobushi).
Okuma's Helm & Arms. (For Shugoki).
Ragnar’s Helm & Ornament. (For Raider).
Ranja’s Helm & Ornament. (For Kensei).
Runa’s Helm & Ornament. (For Valkyrie).
Seijuro’s Helm & Ornament. (For Orochi),
Siv’s Arms. (For Berserker).
Stigandr’s Ornament. (For Warlord).
Stone’s Helm, Ornament, & Arms. (For Conqueror).
Tozen’s Armor & Ornament. (For Orochi).
Tozen’s Alternate Attire. (For Orochi).

Please, feel free to add anything I may have missed or tell if something IS actually in multiplayer!