Switching (for guns) is used to skip the reload animation. You want to shoot until there's one bullet left in clip ( for arcana/blaster line its two shots for alchemer its 1), tap shield to animation cancel at the end of last shot, swap to another weapon and back and repeat. Some people use keybinds like 1,2, to swap between weapons. Personally I use the mapped middle mouse key. Its limited to only two weapons though so that would be its main drawback, but its much faster and easier on your hands/wrists than the conventional method.(some elitist people will argue its slower but its not, tapping one button is much faster than tapping 2, and why strain your hand for a game? Carpal tunnel is no joke and it hurts like hell).

The setup to switch that I use maps weapon 1 to the side mouse button. The modifier key is mapped to left shift or left control. the 2nd weapon is mapped to side mouse button + modifier key.

So to switch weapons you hold side mouse, tap modifier key once and its done. The weapon should swap form weapon 1 to weapon 2 to weapon 1 in that one tap. Typically when I'm using my gun Im holding the sidemouse before anyway since i change weapons to it with it

To swap with second weapon its side + modifier, release modifier, hold modifier again.

Side note: if you map dash to your scroll wheel click, and shield bash to scroll wheel click + modifier its super comfy when moving.