yes if you have amulet with 2 aspects you can check it by going to occultist and select any other aspect and see on preview it will show the lowest possible legendary aspect roll on your first aspect. Then if you reroll again you will get normal roll and lose your second aspect and then cant apply it anymore.
Yea not sure if bug or intended.
As cube should be last step.
It’s intended to allow you to reroll second aspect, not apply to any rand ammy.
So improvement beyond cube isn’t possible, although it’s not marked as “unmodifiable”