think about how overpowered perona's DF is..

1. Can crush a man's spirit completely,
*by logic it can even affect logia, since it hits their spirit, not body.
2. when in ghost form, she's litterally invincible.
*haki can be used to hit the real bodies of logia users , however perona's real body is somewhere else, u cant hit her, shes invincible, and can go through objects, floor etc.
3. When shes invincible, she can create ghosts for offensive, is it possible to put haki in the ghosts to make them more destructive?
4. when shes in ghost form, her real body is technically dead, so even people with observation haki, cannot detect the location of the real body.

She can fly, pass through objects, is invincible in ghost form, and can 1 hit defeat everyone.
Her only weakness is when shes in her real body, or when the oponent knows where her real body is.
Also its unknown what distance she can be from her real body while in ghost form