Exordium is beginning with the case by which one needs to argue. Narratio is the concerns that bring the writer to deal with the situation. Probatio is the arguments and images that uphold the defense. And peroratio is the appeal to emotions. I think that Watson has clearly done a good job at showing how Jude lines up with this framework. One can observe exordium in verse 3 where Jude shows his intention in writing. Narratio is present in verse 4 with Jude intending to write against false teachers. Verses 5-16 and all the references to OT passages of condemnation is a classic example of probatio. And in his conclusion with verses 17-22 being a typically characteristic of peroratio.
The book of Jude is perhaps one of the most neglected books of the New Testament in its inclusion in sermons nowadays. This is perhaps because of the condemning nature of the book and the prevalence of avoiding such speech with fear of offending the congregation. Because Jude offers such a distinct style of poetry and allusion to the OT, it needs to be employed regularly in Bible study and analysis. For one of Jude' emphases is for the Christian to be aware of such people and their ultimate destruction. It is time for the Christians today to publicly read this book and preach it with vitality as was the intention of the author to do the same.