Edit: I didn't state clearly that I don't really think that the narrator is making reference to Helen of Troy, but to a real woman he knows whom he's calling Helen for the possible meaning of the name as referenced in the rest of the post below.
After having read it and thought about it, it seems to me that the narrator's love for Helen isn't physical, even though he recognizes her beauty. Everything that he mentions in relation to her beauty has nothing to do with anything sexual- and it all relates to ancient Greco-Roman civilization. And I think by continually referring to her beauty, he's using her beauty as the personification of her. He's saying her outer beauty is a reflection of her inner beauty; she's a beautiful person.
In the first stanza, he basically says that her beauty has brought him to his "native shore."
In the second stanza, he reveals that the "native shore", the "home" she's brought him to, is the "glory" of ancient Greece and the "grandeur" of ancient Rome. The reference to the Naiads does not seem obvious as far as meaning to me. But the Naiads were goddesses of freshwater springs, streams and wells- things which are sometimes used as symbolic of sources of wisdom, so perhaps that's what he means. She's a source of wisdom.
The third stanza seems in a way a little illogical. He's said she's already brought him "home." But in this stanza, she's standing in a brightly lighted window (opening to the world) with a lamp in her hand (enlightenment, light of education, lighting his path into the world, you name it). Plus, she looks like a statue, and I think he says that specifically to take away any thought of physical desire. Furthermore, agate symbolizes a balance between the physical and the spiritual.
Psyche was an entirely chaste human female, not interested in sex at all, apparently, until after she married Cupid and fell in love. And in modern terms, the psyche is the mind to some, the soul, to others.
I think that what he's saying is that Helen has been an inspiration for him to learn about classical Greece and Rome, and he's complimenting her for it. He wants to make it perfectly clear that he sees her beauty in terms of something other than sexual attraction. Her beauty goes beyond that.
As for her name, Helen of Troy was a woman that men were willing to follow, though not for the reasons the narrator of this poem wishes to follow this Helen- but Helen of Troy's name may have, in itself, been indicative of that quality, that is, that she would be followed.
Searching for an actual definition of the name comes up with conflicting information, but some of the suggested definitions are "torch" and "light", the application of which to this poem would be obvious. And the ancient Greeks are called"Hellenes"- the Greek word for Greece being "Hellas". The name "Greece" is from Latin, and not what the Greeks call/called themselves.
Perhaps you could extend Helen's influence to say that the third stanza simply indicates that she continues to influence the narrator to "better himself."
As I said, I think the poem's intended to be a compliment couched in terms of a shared interest (classical antiquity), and although the narrator's intent on flattering the lady's beauty, he intends to make the flattery as pure as pure can be.