"Iactitasset"

[Subcontrary]

I'm quite flummoxed here! I think I've given a good look at the various possibilities for what that word could mean in this sentence:

"Tandem Petri et Pauli Apostolorum precibus, praestigias ipsius detectas fuisse, et cum in coelum se volaturum iactitasset, ex sublimi decidisse, et extinctus fuisse dicitur."

It looks like some sort of pluperfect form of "iactito." It ought to be subjunctive too since it's part of that "cum meaning 'because'" clause, but the third person singular pluperfect subjunctive of "iactito" is, (according to Wiktionary, anyway) supposed to be "iactitavisset." Maybe it's a typo?? I hate typos!!

Anyway, this is my attempt to translate of the sentence:


"At last by the prayers of the Apostles Peter and Paul, his deceptions were detected, and because he had boasted that he was about to fly to heaven, he was said to have fallen from a high place, and to have been killed."

 

[Bitmap]

Your translation is basically right.
iactitasset is just a shortened version of iactitavisset.
The cum can have an additional meaning like 'because', but it can also just mean 'after' (hard to tell without more context).

The Latin is slightly weird in using fuisse rather than esse and in having dicitur first take an AcI (praestigias fuisse) and then an NcI (extinctus fuisse) ... but ok. That's the one thing I would amend in the translation - dicitur refers to both infinitives: "It is said that (...) his deceptions had been detected and that (...) he had fallen (...) and had been killed."

 

[Pacifica]

The cum can have an additional meaning like 'because', but it can also just mean 'after' (hard to tell without more context).

I'm pretty sure it's only circumstantial here, not causal. It doesn't read very naturally as causal.

The Latin is slightly weird in using fuisse rather than esse and in having dicitur first take an AcI (praestigias fuisse) and then an NcI (extinctus fuisse) ... but ok. That's the one thing I would amend in the translation - dicitur refers to both infinitives: "It is said that (...) his deceptions had been detected and that (...) he had fallen (...) and had been killed."

I suppose it could be that Tandem Petri et Pauli Apostolorum precibus, praestigias ipsius detectas fuisse is dependent on some previous active verb, but I can't tell without seeing more of the text, which I can't find on Google.

 

[Subcontrary]

Thank you both so much for your help!

The passage is here, at the end of the paragraph where the word "Samaria" is highlighted.

 

[Pacifica]

Then, no, praestigias detectas fuisse doesn't depend on any previous verb and dicitur is indeed taking two different constructions at the same time in a somewhat weird way, as Bitmap said.