Malenia is already one of FromSoftware's most infamous bosses, so much so that a summon went viral for beating her over and over for other players, but initially, they were much harder. Count your blessings that she got patched out before launch.
Dataminer kotn3l found a pre-patch 1.0 build where Malenia had another version of her signature move, more aggressive attacks, and better blocking, making her an even more gruelling opponent (thanks, PC Gamer). In the launch build, she has an incredibly difficult-to-dodge flurry attack that can instantly kill even the strongest Tarnished, vampiric draining abilities, two health bars, and more. She might've been flat-out impossible in the unreleased build.
In the original build, Malenia could use her flurry attack the second you initiate the fight, whereas post-1.0, you have to take her down to 80 percent health. And it gets worse. She has two flurry attacks in the unreleased build and each uses its own cooldown meaning she could chain them back-to-back while better blocking your own attacks, doling out serious damage while taking little.
Her ultimate ability, the aforementioned flurry attack, was originally called Malenia's Blade, tied to her sword's description. However, it had less reach and fewer pauses, meaning that it might have been a touch easier. As dataminer kotn3l speculates, this attack was likely repurposed into the Waterfowl Dance.
Malenia is infamous for her first phase alone, but things ramp up in the second when you're already low on healing supplies and willpower. In the original, her Boom Explosion attack was slower, with her using the Aeonia attack much more. She also lacked death dialogue making her fall silently when defeated which is hardly the triumphant victory that we earned on launch.
Next time you're dredging through Elphael, Brace of the Haligtree, pushing toward that treacherous fight, just remember how much harder it could have been. Who knows? Maybe that's the motivation you need to slam a hammer or two into her skull for a quick victory. Or maybe you'll luck out and find Let Me Solo Her doddering about.