Armor sets are the outfits Jin wears in Ghost of Tsushima, and the body piece is the only gear that changes how you play. Each set leans toward a style, such as archery, stealth, standoffs or tanking hits, so swapping sets is how you build for the fight ahead.
Pick a body piece for its perks, then dress the rest however you like. Tadayori's Armor suits bow players, the Sakai Clan Armor suits standoff fans, and the Ghost Armor rewards stealth kills. The Traveler's Attire has no combat perks at all and instead helps you find artifacts and clear fog on the map.
Armorers work in the bigger settlements, such as Azamo Bay, the Golden Temple and Komatsu Forge in Izuhara, Akashima Village and Yarikawa Stronghold in Toyotama, Jogaku Temple in Kamiagata, and Katayama Market and Fune's Refuge on Iki. Each level raises one or more perks, and the first two upgrades usually give you new headgear or a mask too.
Dyes recolor a set and do nothing else. You get them from tales or buy them from merchants with flowers, and New Game+ adds more at Baku the Voiceless for Ghost flowers. Three sets get no dyes at all: Hero of Tsushima, Deadly Rival's and Archery Master's. Sakai Horse Armor dyes come from Tsubaki on Iki once you find enough Sakai Banners.
Archery Master's Attire
The Archery Master's Attire is Sensei Ishikawa's outfit, once a New Game+ armor set and now a dye for Tadayori's Armor. Its archery perks match a fully upgraded Tadayori's Armor, and you buy it from Baku the Voiceless with Ghost flowers.
Broken Armor
The Broken Armor is the damaged samurai armor Jin wears through the Prologue after the Battle of Komoda Beach. It is the only set with no perks at all and it cannot be upgraded, so wear it only for the look or as a self-imposed challenge.
Deadly Rival's Attire
The Deadly Rival's Attire is Ryuzo's outfit, which Baku the Voiceless sells for 50 Ghost flowers in New Game+ only. It gives a massive health boost, major melee damage and stronger Ghost weapons, and it has no upgrades.
Fundoshi
The Fundoshi is a loincloth outfit you earn by resting at 18 Hot Springs in Ghost of Tsushima. It has one trick: running and sprinting make no noise, so you can rush up behind enemies for assassinations without crouching.