Shattered Mask of Tomoe is a mask you get by finishing "Laid to Rest", from Ishikawa's tales, part 9 of 9. It is a story reward, so playing the tale is the only way to add it.
Play "Laid to Rest" to the end and the mask comes with the rewards.
Charm of Precision
The Charm of Precision is a minor Ranged charm in Ghost of Tsushima. Your arrows deal a moderate amount of extra damage. You get it by finishing The Past Never Passes, Dreams of Conquest or Laid to Rest.
Midnight Shark
Midnight Shark is a dye for the Half Bow. It is a reward for completing "Laid to Rest" (Ishikawa's tales, part 9 of 9). Like every dye it only changes colours.