Find your tribe in a Sea of Creativity
I'm working on a longer SA/HP story, but this notion got into my head. It won't fit in the larger story, but it also won't leave me alone:
In the Harry Potter universe Kaladin finds out about horcruxes when Syl passes through an object without appearing to harm it (maybe he is going on a rampage in the room of requirement which gave him things that he could destroy to relieve stress and he comes across the diadem?). When Shardblades pierce living things, they kill or cut off the soul rather than harming the physical shell, so it stands to reason that a shardblade passing through a horcrux would destroy the soul piece instead of the object. He eventually learns about the horcrux in Harry and has Syl manifest as a scalpel so he can remove the soul piece from Harry's scar.