God I hated that bitch. I'm too old to memorize animations and react to them. I so just wanted to spam her to death. I probably tried 100 different gear setups and failed all of them and quit for a month. I've heard that you must discipline yourself to "hit just once" and then you will pay more attention to reacting to the animations and then you will learn them. But I never learned them. I'm too old and too in-my-head to be the fast-twitch sensory reactor necessary to excel at this kind of game. But I'm nothing if not determined, and so by luck eventually one of my many attempts worked.
Whatever stories i hear about Malenia they all boil down to basically this story. Go in, fail often, change random things to min/max. Still fail. Tear hair from head. Question life decisions. Randomly do it.
In order of difficult for me: Malenia blade of Miquella, Twin Gargoyles in Siofra Aquaduct, Malaketh the Black Blade, Radahn and Elden Beast maybe tie for fourth I'm not sure. Ridiculously easy: Ser Gideon Ofnir the All-Knowing, Renalla Queen of the Full Moon. Both killed first time without even knowing how they fight.