Soul Arrow now stacks with +Attack Arrows.

Are you sure the damage is serverside not clientside? Seeing bigger numbers doesn't guarantee that its being registered by the server as doing more damage.

Will a 4 att increase have a noticable decrease in the time it takes to kill a pap? (Maybe testing second body with a constant kb).

Count me as a skeptic but this game has enough glitches.

Go run around killing stuff without attack arrows for a few minutes and then get some attack arrows, and try again. Tell me if you notice a difference in your maximum damage. I did.