What is "Black Armour Piece" used for?

You also need a Flaming Feather to make a Black Feather, which is used for another quest. No idea which, though, I procrastinate on all the old Victoria quests just because they're so damn annoying and pointless. "Kill 500 Red Snails, Lupins, and Tauromacis! Collect 100 Jr. Balrog balls! Thanks, have 800 exp and a defense scroll!" After 2 hours of hunting stuff for a level 50 quest I should at least get 150k exp or something if not a 60% weapon scroll or SOMETHING that might make me feel like I didn't TOTALLY waste my time.