Hi,
I am considering you are using form with single source. If the two fields that you mentiond are from same source that you gave to the form or in two different entities. In that case you can use local variable for validation and for create and update assign the value.
If ReasonForEdit="" or ReasonForEdit =Nulltextidentifier()
then feedback message,
Else next step
Like wise
If Justification="" or Justification=NullTextIdentifier(),
Then feedback message,
Else next step
Hope this will help,
Rrgards,
Komal