One must separate evaluation of a particular utterance from evaluation of a speaker's capacity, and also distinguish fasāḥah from balāghah.
Technical descriptionPrimary criterion
Fasāḥat al-kalāmAn utterance free of linguistic and semantic defects
Balāghat al-kalāmAn eloquent utterance fitting its context
Fasāḥat al-mutakallimStable capacity to form eloquent utterances
Balāghat al-mutakallimStable capacity to form contextually suitable eloquent utterances
Kalām concerns a specific expression; mutakallim concerns the speaker’s established ability.