I'm happy that I found this new word τρίστομος in LSJ today, and would like to share my happiness.Revelations 1:16 wrote:καὶ ἐκ τοῦ στόματος αὐτοῦ ῥομφαία δίστομος ὀξεῖα ἐκπορευομένη
It is comforting to know that besides δίστομος there is a word τρίστομος referring either to a three-edged or three-pointed αἰχμή ("spear-point"), or to a τρίαινα / τριόδους trident as τρίστομον δόρυ ("spear").
Finding it at least sets my mind at easy that δίστομος is good idiomatic Greek - rather than bad Greek on the part of the authour of Revelations - even if talking of the mouths of swords (and now spears) is a non-English idiom.