They are the fair maidens who guard graves. You have one assigned to you during your life — a sort of guardian angel — and when you die she sits around watching your grave to make sure you’re comfortable.
The LASAS are associated with personal destiny in some obscure way. Perhaps during your life they nudge and guide you along your allotted path. After all, there’s not a lot they can do when you’re dead.
They have wings and wreaths — fair enough — but they also carry mirrors, which is a bit mystifying. Is it to check that the inhabitants of their realm really are dead? You know, hold a mirror to the lips for any sign of a breath misting the glass.