The Charm of Unyielding II is a minor Defense charm in Ghost of Tsushima. While you are at half health or below, you take a major amount less damage. You get it by finishing the tale Ghosts in the Fog.
Complete Ghosts in the Fog and the charm is part of its reward.
Noble Fighter's Headband
Noble Fighter's Headband is a headband you get from "Ghosts in the Fog", a side tale (Norio's tales, part 3 of 9). There is nothing to search for: play the tale and it arrives with the rewards.
Akashima Bamboo Strike
The Akashima Bamboo Strike is a sword-timing challenge near Fort Ito in Toyotama. Cut through all the bamboo with the right buttons and it counts toward raising your maximum Resolve.
Akashima Haiku
The Akashima Haiku is a poem spot where the river meets the sea, just south of Old Kanazawa Marsh in Toyotama. Sit down, pick three lines and you earn the Headband of Uncertainty.
Akashima Lighthouse
Akashima Lighthouse is one of the 10 lighthouses Jin can relight, at Fort Ito, Toyotama. Lighting the fire gives a minor boost to your Legend.