You mean the weapons and armour that are not artefacts?

Using the magic transmute spell you can transmute (keep) anything. That's how you can get the mountain berries for the man in the inn.

The transmuted items will not be able to be stored in the museum.

Yes i discovered that about transmute.

But i didn't notice transmuted items aren't accepted in museum.

Thx for info.

That's okay :) Yeah it can be really hard to fill up the whole museum.