The Traveler's Attire is the exploration outfit a merchant hands Jin soon after the Prologue. It has no combat perks, but it makes the Guiding Wind point to artifacts and clears more of the map's fog, so it is the set to wear while collecting.
Talk to the first merchant you meet after the Prologue and the outfit is yours. It replaces the damaged armor Jin starts in.
Wear it whenever you are hunting collectibles. Picking the Guiding Wind from the map switches Jin into it automatically. Since patch 1.06 a firefly also guides you to nearby artifacts and blinks faster as you close in. The cape hides both bows.
Aaruul
Aaruul is one of the 50 Mongol Artifacts, pieces of the invaders' culture and warfare you can study. It sits at a camp south of Izuhara Clearing in Izuhara, and finding 20 artifacts counts toward the Know Your Enemy trophy.
Adachi Dragon Mask
Adachi Dragon Mask is a New Game+ mask sold by Baku the Voiceless for 5 Ghost flowers. It does not exist in a first playthrough.
Adak Tree
Adak Tree is one of the 50 Mongol Artifacts, pieces of the invaders' culture and warfare you can study. It sits at Yoichi's Crossroads in Izuhara, and finding 20 artifacts counts toward the Know Your Enemy trophy.
Adventurer's Fortune
Adventurer's Fortune is a dye for Traveler's Attire. It costs 10 flowers at the Izuhara merchants. Like every dye it only changes colours.