Vanity gear is easy to come by naturally.
You can buy them from merchants, things likes armour dyes, sword kits etc.
You can also gain sword kits from Pillars of Honour strewn around the map.
Masks are gained from the Golden Temple at intervals, by checking the gift altar regularly.
Headbands are earned through either story progression or by composing Haikus, in marked map locations found by exploring the map in free roam.
Horse Saddles are earnt through collecting banners and returning them to the Monk at Kamatsu Forge.
Armour itself doesn't seem to count as it offers bonuses once upgraded.
To summurise, the items that count are
• Sword Kits
• Armour Dyes
• Horse Saddles