Pretty sure it's dictated by the Camera Visual Smoothness slider, located in SharpeYe menu > Details > Focus mode Options. Setting it to 0 turns it off, disabling the weapon sway almost entirely. I'd recommend values 9 and below for responsive camera movement and values 10+ for slow/delayed camera movement.

Lastly, make sure to use Relax mode instead of Focus mode if you want to use values of 9 and below. The camera gets extremely jittery if you're in Focus mode at these values.