Armor of the Colossus is a dye for Ghost Armor. You earn it by completing the Shrine in Shadow, one of the Wind Shrines that reward special armor dyes. Like every dye it only changes colours.
Find the Shrine in Shadow and clear it. The dye is part of the reward, together with a piece of vanity gear from the same shrine.
Once unlocked it shows up as a colour option for Ghost Armor, so you need that outfit to use it.
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.
Amber Assassin
Amber Assassin is a dye for Ronin Attire. It costs 10 flowers at the Toyotama merchants. Like every dye it only changes colours.
Ancestral Force
Ancestral Force is a dye for Sakai Clan Armor. It costs 10 flowers at the Toyotama merchants. Like every dye it only changes colours.
Archery Master's Attire
Archery Master's Attire is a dye for Tadayori's Armor. It is a New Game+ dye sold by Baku the Voiceless for 15 Ghost flowers. Like every dye it only changes colours.