Its an interesting point Kyron. Something else to add to the confusion is when Makuta talks about him being nothing.
If you somehow manage to destroy Nothing, what are you left with? Quite simply, you are left with nothing. You have not succeeded.
One way of getting rid of Nothing could be to put Something in its place. I believe that this 'something' is light.
Darkness is simply a lack of light. But Light is not a lack of darkness. So Takanuva must fill the void of Shadow with light in order to defeat it.
And yes you are wierd.