What is the grammar of ‘quid illud quod’ in Ambrose De. ob. Val. 35?

Question

Introduction and question

Ambrose is generally not too hard to read; his structure is pretty straight forward, his word-choice is not too weird, and he seems to have favoured a style which would be easily understood by his congregation, which after all was not made up of the one-percenters of the one per cent. (Of course, as most of us, I am reading an English translation, then consult interesting passages in the Latin, then do my own translations back to English). One phrase I encountered today proved to be more difficult than anticipated, though:

Latin:
Quid illud quod morī nōn timuit? Immō prō omnibus sē obtulit dīcēns quod frūstrā propter sē aliī perīclitārentur: sibīque potius mortem optābat, nē ipse aliīs causa mortis esset.

Very verbatim:
What/Which that which he did not fear to die? Quite the opposite: For everyone himself he offered, saying that for no purpose because of / by means of / through himself others were put in danger: and for himself instead/rather death he chose, not himself for others to have been the cause of death.

Normal English:
What/Which [thing? -> fact?] that he did not fear to die? Quite the opposite: He offered himself for everyone, saying that for no purpose others were put in danger because of himself: and for himself he rather chose death, for fear that he himself would have been the cause of death for others.

In Conloqvivm, Joonas said that:

For the lack of a better word, quid illud quod might be better treated as a “phrasal cluster”. Much like the French qu’est-ce que il y a should not be analyzed as “what is it that it has there” but “what is it”.

My follow-up question, which is the question at hand here, is simply this:
What exactly is going on grammatically then?

I was from this encouraged to ask this publicly, as it seems to pose grammatical challenges which ‘deserves proper analysis in front of all eyes.’

Other translations

Liebeschuetz and Hill suggest ‘What of the fact that Valentinian was not afraid to die?’ But I am unable to understand how they get ‘of the fact’. Joonas said that ‘Literally it seems to be quid [est]* illud quod, a relatively simple relative clause, but understanding and translating (in that order!) quid and quod well† is hard.’

Remarks

* I have noticed that Ambrose seems to not bother with forms of esse; I have encountered at least one instance of accusative with infinitive, where there was no (intransitive) verb. As far as I know, this was common, but it should be worth noting; also, I have heard this is not uncommon in other heavily inflected languages, such as Russian, ɔ: the verb to be is not important to utter for a sentence to carry proper meaning. E.g.:

• Asked to a male, informal: Ты голодный? – [Are] you hungry?
• Asked to a male, formal: Вы голодный? – [Are] you hungry?

My Russian friend whom I asked for these sentences, said that it was actually hard to figure out how the verb would be in these sentences, which I would dare say perfectly illustrates the point.

† It is interesting how not having ‘well’ surrounded by commas, changed the meaning of that sentence from Joonas up there.*

Answer 1

I would say that illud might be translated as that, referring to the subordinate clause introduced by quod, which might also be translated as that:

Quid illud quod mori non timuit?

What [is] that that he didn't fear dying?

This use of illud is described by Allen and Greenough:

e. The pronouns hīc, ille, and is are used to point in either direction, back to something just mentioned or forward to something about to be mentioned.

f. The neuter forms often refer to a clause, phrase, or idea.

They also mention this particular use of quod:

572. A peculiar form of substantive clause consists of quod (in the sense of that, the fact that) with the indicative. The clause in the indicative with quod is used when the statement is regarded as a fact.

This is also consistent with the translation you provided by Liebeschuetz and Hill, in which illud quod would be translated as the fact that:

What of the fact that Valentinian was not afraid to die?