Mr. Notheff provides the following information due his outrage that this store of Witcher Wisdom lacks catlike armament information.
Mastercrafted Feline Armor: Found in Skellige, on the island of Faroe. From the village of Trottheim, head due south to the coast. Once reached, follow the coast west to find the monster-den cave (Sirens surround the entrance). Once inside, head along the North branch, past the statues, and you will find the chest tucked behind stalagmites.