Is a direct object missing here, something like τοῦτο, because otherwise ἕρμαιον and εὐτύχημα are as if suspended in the air?: ἡγούμενος δὲ αὐτὸν ἐσπουδακέναι ἐπὶ τῇ ἐμῇ ὥρᾳ ἕρμαιον ἡγησάμην εἶναι καὶ εὐτύχημα ἐμὸν θαυμαστόν, ὡς ὑπάρχον μοι χαρισαμένῳ Σωκράτει πάντ᾽ ἀκοῦσαι ὅσαπερ οὗτος ᾔδει. Οtherwise, it may also be understood as following: (Stephanus’ translation): quum vero aliquando arbitrarer eum de mea forma valde esse solicitum, opportunam felicemque hanc occasionem divino quodam numine mihi obtigisse existimabam ( I thought that there was an opportunity and a happy occasion sent to me by God). Another question: Stephanus’ translation continues as follows: quod dum Socrati gratificarer, ea omnia audire possem quae ille noverat. While ‘noverat’ is certainly no mistake, if taken to stand for an objective remark outside oratio obliqua, however, would classical Latin not have used here ‘novisset’?
I spend a lot more time trying to make sure I understand your questions than coming up with an answer. It makes perfect sense without supplying anything extra, and I fail to see how ἕρμαιον and εὐτύχημα are hanging in anyway. ἕρμαιον is either a substantive coordinate with εὐτύχημα, or more likely a predicate with καὶ being intensive, “I regarded it as an especially rare stroke of divine fortune…” Supplying something like “it” or “this” is necessary to smooth out the English, but is not required in Greek.
As for your Latin questions, the subjunctive is regularly used in relative clauses in indirect statement unless the writer wishes to indicate that the action of the verb in the subordinate statement is his opinion as well, and then the indicative is used. A relative clause “outside oratio obliqua” that is also “objective” would demand the indicative.
thanx for the clarification
Questions which make us thing about the text are always good (I’m clarifying my response above, just in case anyone thought it had a negative connotation). I should add that it’s actually the accusative+ infinitive clause that’s the direct object of the verb. In English, we often need an expletive such as “it” or “this” to “fill out” the sense in translation.