Board Thread:Theories and Speculation/@comment-44142243-20200416151624/@comment-6769189-20200421105932

Look at the scan.

"What is up with that sword"

"No wonder no ones been able to locate it, its a spirit blade that has no physical form"

Zetsu is learning the truth about the nature of the sword in that moment. These arent facts that he already knew, otherwise he would say something along the lines of:

"Oh, its the Totsuka Blade. It doesnt have physical form so no one should have found it"