What's the lore behind Midir? I'm guessing the “Darkeater” part comes from something about the abyss? That's the only thing I could come up with since the abyss tends to come up
Dark Souls 3 - Where to Find and How to Defeat Darkeater Midir (Boss Guide)
Black Knight Greatsword | Dark Souls 3 Wiki
Dark Souls 3 - Darkeater Midir Taken On With A Broken Sword - GameSpace.com