Ghost of Tsushima: Sea Dragon's Wing

Ghost of Tsushima's Sea Dragon's Wing is a sword kit with the description "Summon the fierce courage of a dragon." It is one of the appearance upgrades for the Sakai Katana that you can buy from merchants.

Summon the fierce courage of a dragon.

Acquiring Sea Dragon's Wing

You can buy it from merchants at the cost of 15 flowers.

Merchants sell not only sword kits, but also bow kits, armor dyes, and hats. 

Visit our Ghost of Tsushima 100% Walkthrough to get more details.