I wonder if Defender Greatsword will get nerfed. Even without its self-buff it can hit quite hard
That's an understatement, in a hands of Faith build with high stats it hits like fucking ultra-greatsword with it's Lightning scaling even without buff.
Honestly, I have no idea if there's a good solution to this.
Make multiplayer good? Allow hosting passworded games so only bros could join so you can finish game jolly-cooperating with your friend. Allow hosting games per-location with dueling/free for all systems, and add mutators on top of it like "only longswords", "no healing items". Allow creating games where anyone can join freely too and kill anybody, like Hardcore in Diablo, and give achivements for it.
This sort of stuff was p. standard in shooters back in the day and even in single-player 3d person action games. Let people pvp in controlled environment to their heart's content ffs.