The passage in question is universally regarded as one of the most corrupt in all of Irenaeus. Indeed as we noted in our earlier post, the 'half letter' is elsewhere identified by Irenaeus as the episemon (= ו). As such it has to stand to reason that corruption has entered the passage again and the original text identified two 'Hebrew' words ישו and ברו where the ו in each 'name' is understood to be the 'dimidia' (= half letter) at the end of each word.
Of course the obvious objection to this reconstruction is - what the hell does ברו mean? The answer I suspect is Irenaeus took it to mean 'his Son' just as he read the ברא in Genesis 1:1 to mean 'the Son.' (Proof 43). It is always dangerous to reconstruct ancient misunderstandings like this. But it has to be said that Irenaeus's 'Hebrew' as reflected in the surviving manuscripts is simply a joke. Now most people take Irenaeus's reference to 'Hebrew' as meaning 'Aramaic.' But it is clear from the transcription in Proof of the Apostolic Preaching that Irenaeus is using the Hebrew text of Genesis chapter 1 rather than an Aramaic or Syriac translation.
Was Irenaeus reading the Hebrew text as Aramaic? This would boggle the mind in its complexity. The obvious way out is to claim that Irenaeus was totally incompetent in Hebrew. But there is a compromise position. The late Hebrew of Proverbs 31:2 uses בר to mean 'son'
מַה-בְּרִי, וּמַה-בַּר-בִּטְנִי; וּמֶה, בַּר-נְדָרָי
What, my son? and what, O son of my womb? and what, O son of my vows?
To this end, the second 'two and a half' letter word cited by Irenaeus - i.e. ברו - must have been taken by him to be a late Hebrew noun or 'his Son.' This would explain, at least, in part where he got the crazy idea that 'the Son' appeared in Genesis 1:1.
Of course that is not the end of matters. Not by a long shot. We have to consider whether Irenaeus could actually read Hebrew. This seems unlikely given the fact that one would think that the rest of his reconstruction would leave Genesis 1:1 without a verb. But the text is so garbled it is hard to make sense of it:
Now that there was a Son of God, and that He existed not only before He appeared in the world, but also before the world was made, Moses, who was the first that prophesied, says in Hebrew: Baresith bara Elowin basan benuam samenthares. And this, translated into our language, is: "The Son in the beginning: God established then the heaven and the earth."
Is 'basan' a new verb that has been added to the opening lines of Genesis? We simply can't be sure other than to say that 'samenthares' seems to transliterate 'and the earth.'
It is hard to say whether Irenaeus actually could read Hebrew. My sense is that he certainly thought he could read Hebrew and perhaps he knew a few basic rules of conjugation and grammar. To this end he may well have known that ברו = 'his Son' just as the heretics - and the Samaritans - knew that אִישׁו = 'his Man.' Seen from this perspective it is not surprising that Irenaeus put forward both ישו and ברו in his tirade against the heretical interest in the name of the Christian god. Over and over again in the first book of Against Heresies Irenaeus tells us that the heretics began with a quaternion (= i.e. four first principles). In other words, lurking in the background of his two examples of the divine name of the Christian god - ישו and ברו - is the actual term used by the heretics themselves i.e. אִישׁו
