Well, again, this is the issue of the Englishman's language mindset vs. the ancient Greek guy's language mindset. Of course, it is dative case, not a prepositional phrase. There is no preposition. Adding the preposition "to" in English changes it into a prepositional phrase, such as "to the eyes." (Flashback to 11/10/2022 "'the' or 'his' spirit": I'm glad the claim is not being made that "τοις functions as a preposition.") And "Dative of Means" is not a Greek language construct, but an Englishman's translation construct. Because if we could turn back the clock and back-translate the words "Dative of Means" to an ancient Greek guy, I think he would just scratch his head trying to figure out we were talking about. It gets worse. If you choose the preposition "with" then, hyper-literally in English, you might wonder how the thing that is seen is sitting "alongside" someone's eyes. So, now you would have a potentially ambiguous English construct to explain, breaking the preposition "with" into semantic categories! I have found it helpful to just illustrate the Greek dative as with simply an arrow pointing to the thing of interest, and the genitive with an arrow pointing from the thing of interest, and just picture it in my mind with an arrow. The light from whatever we "gaze" at really does go in the direction "to" our eyes. So, in conclusion, I would still use the preposition "to" in English. That's awkward English, but I personally don't care. To my eyes (pun intended) it makes sense. If I'm reading ancient Greek, I'd rather become accustomed to how Greek guys wrote than how Englishmen write.