When using a gun, I often find myself just short of hitting a target. It would be nice if the color of the mouse cursor changed based on the range of the current gun.
If the location of the mouse is out of range of the current gun, make part of the cursor red. In range, normal color. It helps us aim, and gives us some feedback on which weapon we have currently selected, without needing to look at out character or the HUD. At that point, it's up to us to judge the speed of the target and of our projectiles.
Sword users, due to their melee range, are usually looking at their character. And, if they miss, their next swing will auto-target and likely hit.
A laser sight would probably be over-the-top, but maybe useful for those of us who use controller pads instead of the mouse.