I know you said you wanted a more general answer than astrology, but it really is the best guide for understanding how the body connects with the soul. Certain planetary influences can have affect on certain parts of the body and its shape and health, the same way each astrological sign is tied to a major part of the body. Composition of the elements in the chart can also influence appearance, other physical traits and emotions, but it’s not so clear cut. I mean, think about how complex the systems in your body are alone. That’s a reflection too. The soul is just as complex and even harder to understand.
The problem with finding one for one comparisons like your example, air element being represented in blue eyes, is too simplified and it would take forever to list all the influences and cross influences that would reflect something like that. Because there are people with blue eyes with little air element in their soul. But if you know how the air element represents itself in all its different ways, you’ll recognize the traits when you see them, even with a basic understanding.
For example, I know someone that has a chart almost exactly like mine right to the degree, but we do not look like twins, or really all that similar. We don’t even have the same eye color. But we have the same element prominent in our souls and it’s not hard to tell if you know what you’re looking for.