"Taking it" is not the same as "using it"None of the theories in here make any sense. You need an immense amount of chakra to be able to use them.
I hope it is just sealed inside the gourd with Ginkaku. That weapon held very little interest for me.
So it still makes sense if a Zetsu had taken it to Madara/Tobi.
And I don't think it would be inside the gourd, b/c then it wouldn't be worth mentioning that its missing....
Anyways, there aren't many options of who would've taken it...Zetsu, or an edo tensei'd character...
If a good guy had picked it up, surely we woulda seen that...