I sorry i cant help more
to be honest i never fully sorted it myself
i bought the simplymaya low poly man rigging tut
im gonna rig my dragon once its finished
if the tutorial tells me anything...

check the weights for the shoulder wrist tip and everything
all of my joints near the hand were really messed up
BTW youre penguins much better than mine

Yeah i had this problem with the penguin as well
the book forgot to mention you would need to sort out the paint weights