The constructed language Lojban has a word especially suited for performative utterances. The word "ca'e" is a sort of exclamation, meaning something like "I define," and can be used in utterances of this type to indicate that by saying it you make it so. I suppose a similar concept might be "Fiat."
Lojban has many words of this type, indicating the speaker's emotions or relationship with the utterance or some aspect of it.