Aim offset is quite the thing. I was looking for a way to not make the camera rotate when the torso rotates. Thing is, the camera and the torso plus the spine bones rotate at the same time in my original setup. This way, the camera ends up pointing at the character's stomach when looking all the way down, when the camera's center should actually be pointing at the feet. Then there's also the fact that the weapon can't be seen when looking all the way up, and it's at the top of the screen when looking down.
To bypass camera rotation, I told the Add Controller Pitch Input to go fuck itself, and afterwards I tried setting a float variable through the InputAxis event. This float controlled the bones, just the bones. But it didn't work as expected. Clients couldn't replicate the rotation; I jammed a Run on Server event in the middle of the logic, then it did work. And it stuttered quite a bit, obviously. Input events are fired every frame, so updating rotation in Blueprints over the network every frame isn't going to be too efficient. The final solution kek which I hope will the the ultimate one, is to leave everything as it was before, and setting the camera's sensibility way down low. That way, I'm just reducing the problem drastically, at a point where it doesn't really matter.