Archimedes can give you an aging point if you answer his question correctly
xanthos can give a hop randomly

The only divine horses that you can interact with for prizes without needing to be the owner of them are;

Frost. You can defrost one a day, for a chance to win a Hypnos' Blanket. It's a decently high chance, too, and happens pretty often.

Archimedes. You can answer their horse trivia questions each day. The first Archimedes you correctly answer in a day will give you an ageing point.

Topaz. You can congratulate 5 of them each day. You'll 50 Equus per Topaz, or you have a tiny, tiny, tiny, infinitesimally small chance of getting some passes instead.

Xanthos. You can stroke 5 Xanthí each day. The first Xanthos you stroke in a day will give your most recently born horse +10% energy. After the daily update, each Xanthos gives a Horn of Plenty to one randomly selected player from among those that stroked that particular Xanthos the previous day. If you pick 5 good Xanthí that aren't being stroked by many other players, then you can get several Horns of Plenty each week this way.

To add: you can only answer 1 Archimedes' question each day. For a good answer he gives you an aging point.

If you're in need of the correct answers, I have them in my EC forum. Credits to CraXor who made a webpage about it long ago, that webpage is broken now. (I filtered out a few wrong answers, they are all correct now.)

[If you pick 5 good Xanthí that aren't being stroked by many other players, then you can get several Horns of Plenty each week this way.[/quote]
How do you find good ones?

You don't know that until the next day

But a good advice is to not choose the ones on popular player's pages (because they get many visitors and lots of people will stroke them), not choose the ones on the very first or last pages (the 'visible' pages in the list so to speak - because, indeed, everybody does) and to keep the notifications Howrse sends you about Xanthos and re-stroke those.

It's never a guarantee!! But it can increase your chances a bit.

[quote]

Frost. You can defrost one a day, for a chance to win a Hypnos' Blanket. It's a decently high chance, too, and happens pretty often.

Topaz. You can congratulate 5 of them each day. You'll 50 Equus per Topaz, or you have a tiny, tiny, tiny, infinitesimally small chance of getting some passes instead.

[/quote]


Well, I don't know.
Frost gave me a blanket in much the same way Topaz – passes.

The chances of getting the "big prize" from any divine that you can interact with as a visitor, are very small. You can get lucky, but most days you just get nothing (or, in Topaz' case, just equus)