Most of the armor and weapons in the game are randomly dropped by enemies or Bosses, but some special sets are unlocked by completing specific missions and defeating Bosses. Successfully complete the indicated task to get the corresponding armor or weapon set:
Crusader Set: In the area with the pair of armored knights in the Tower Of London in the “Prologue”, enter through the open gates. There are two treasure chests in the exterior section that always drop parts of the Crusader Armor set. You can also kill the pair of crusaders at the tower entrance that leads up to the Shrine and the Derrick The Executioner boss. They will randomly drop Crusader armor parts.
Ninja Set: Successfully complete “The Way Of The Ninja: Novice” dojo mission. It is unlocked after completing the first main mission in the Kyushu region — and gaining access to the world map.
Raging Bull Set: Successfully complete the “Deep In The Shadows” (second) main mission to unlock the “Finders, Keepers” side mission in the Kyushu region. Complete the “Finders, Keepers” side mission to unlock the Raging Bull Set.
Warrior Of The West’s Honor Set: It is randomly dropped by the final Boss of “The Spirit Stone Slumbers” main mission, Tachibana Muneshige, in the Kyushu region. Defeat him multiple times to get all the drops — or fight him again in the “Invitation From The Warrior Of The West” side mission that becomes available after completing this main mission. However, the fight against him in the side mission is significantly harder compared to the first battle against him in the main mission.