Allomancer Alex

After doing more digging I guess multiple people have healed from a shardblade cut (e.g. kaladin) in the earlier books. Been too long since I read them. So I'm assuming Lift is back to normal.

Is Lift able to heal herself with her lifelight (or any other way)? Are shardblade cuts permanent in the physical realm? Maybe I missed something, but it wasn't clear to me if she did this after her incident with Moash?

I was wondering what happens to atium once it has been burned? As far as I am aware atium is the body of ruin/ati and is physical form of Investiture. I understand that "Investiture works in a similar fashion to energy in that it follows its own laws of thermodynamics and that it is not possible to destroy Investiture; it can only be redistributed." Preservation had the mists snap people to become atium mistings so that they could burn away the atium cache so that ruin couldn't get a hold of it. But, where does that physical Investiture go to (e.g., the cognitive or spiritual realm?) and why can't ruin access it after it has been "redistributed"?