In your second example, ὅστις δ᾽ ἀφικνεῖτο τῶν παρὰ βασιλέως πρὸς αὐτὸν, the text reads imperfect indicative ἀφικνεῖτο where I would have expected optative αφικνοιτο. In fact, at least one late 15th c. manuscript does read αφικνοιτο, but Marchant’s OCT rejects this, insisting that this manuscript is full of errors. Presumably Marchant thought that the αφικνοιτο reading is a conjecture by a copyist who expected the optative here, like me.
Smyth cites this passage as an exception in 2569a, below. Here is his discussion of what he calls “conditional relative clauses” (i.e., general relative clauses, which are equivalent to general conditions), with some extraneous material omitted and the main “rules” in bold:
2567. Present general conditional relative clauses have ἄν with the subjunctive. The main clause has the present indicative or an equivalent.
νέος δ᾽ ἀπόλλυθ᾽ ὅντιν᾽ (= εἴ τινα) ἂν φιλῇ θεός ‘he dieth young, whome’er a god doth love’ Stob. Flor. 120.13, οὓς (= εἴ τινας) ἂν ὁοᾷ φιλοκινδύ_νως ἔχοντας πρὸς τοὺς πολεμίους, τι_μᾷ whomever he sees zealous of danger in the face of the enemy, these he honours X. H. 6.1.6, ““γαμοῦσί τε ὁπόθεν ἂν βούλωνται, ἐκδιδόωσί τε εἰς οὓς ἂν ἐθέλωσι” they both get a wife from whatever family they please and give their daughters in marriage to whomsoever they choose” P. R. 613d, ““πατρὶς γάρ ἐστι πᾶσ᾽ ἵν᾽ ἂν πράττῃ τις εὖ” for every land is a man’s own country wheresoever he fares well” Ar. Plut. 1151.
http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0007%3Asmythp%3D2567
2568. Past general conditional relative clauses have the optative. The main clause has the imperfect or an equivalent.
ἀεὶ πρὸς ᾧ (= εἰ πρός τινι) ““εἴη ἔργῳ, τοῦτο ἔπρα_ττεν” whatever work he was engaged in, that he always performed” X. H. 4.8.22, ἔπραττεν ἃ δόξειεν αὐτῷ he always did whatever he pleased D. 18.235, ““πάντας . . . ὅσους λάβοιεν διέφθειρον” they used to destroy as many as they captured” T. 2.67, ““ἐθήρα_ ὅπου περ ἐπιτυγχάνοιεν θηρίοις” he used to hunt wherever they fell in with large game” X. C. 3.3.5, ἀνέκραγον . . . ἱκετεύουσαι πάντας ὅτῳ ἐντυγχάνοιεν μὴ φεύγειν they screamed out, entreating all they met not to flee X. C. 3.3.67.
http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0007%3Asmythp%3D2568
- The present indicative instead of the subjunctive with ἄν occurs in general conditional relative clauses (cp. 2342). This occurs chiefly after ὅστις, which is itself sufficiently general in meaning.
““οἵτινες πρὸς τὰς ξυμφορὰς γνώμῃ ἥκιστα λυποῦνται, ἔργῳ δὲ μάλιστα ἀντέχουσιν” those who in feeling are least depressed at misfortunes, in action resist them most” T. 2.64, ὅστις δ᾽ ἐπὶ μεγίστοις τὸ ἐπίφθονον λαμβάνει, ὀρθῶς βουλεύεται he counsels wisely who incurs envy in a great cause 2. 64, ““ὅστις δὲ πλοῦτον ἢ εὐγένειαν εἰσιδὼν γαμεῖ πονηράν, μῶρός ἐστιν” whoever fixes his gaze on wealth or noble lineage and weds a wicked woman, is a fool” E. El. 1097, ““ὅ τι καλὸν φίλον ἀ_εί” whatsoever is fair is dear forever” E. Bacch. 881.
a. Cases of the imperfect instead of the optative are rare and generally ill supported: ὅπου ᾤετο τὴν πατρίδα τι ὠφελήσειν, οὐ πόνων ὑφί_ετο whenever he thought that he could benefit his country in any respect, he did not shrink from toil X. Ag. 7. 1. Cp. X. A. 1.1.5, 1. 9. 27.
http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0007%3Asmythp%3D2569