Board Thread:Show-Related Questions and Answers/@comment-1423293-20151221002320

In "Swan Song", we find out that Gold used some undefined magic to turn Excalibur into a conduit that would pass on the Darkness into him if it was wiped from all other sources.

My question is: why does it make Excalibur turn into dust and reform as the dagger? Wasn't the dagger just a piece of Excalibur that was broken off?  