Nope, Chameleon Cloak doesn't do that. I don't believe that 2 AP penalty can ever be negated during combat.
Being able to swap weapons during combat might give you a lot of advantages, if you do it right. Being able to do it repeatedly without any kind of penalty is way too convenient. Putting your equipped weapon(s) into your backpack, pulling the new ones out, equipping them - doing all that has to take up *some* of your time. It wouldn't make sense otherwise.
