If you are confused about how to dress up as a Legendary Thief aka Cooper Clan Cosplayer Trophy then here is the list:
Crooked Kama Headband
Gosaku’s Armor (with Ocean’s Guardian dye) - You can get this dye from mostly any Merchant, I got mine from the one in Yarikawa Stronghold.
This is the final output:
You’ll get all these items as you explore the Tsushima world, you can equip yourself with the Traveler’s Attire first (upgrade it to max) and you can use your technique point to get “Wind of Vanity” to guide you, it’ll help you to get items that can personalize your appearance.
This Silver trophy is a MUST if you want to get the Platinum Trophy for this game. Do let us know if you have any other queries.