There seems to be two questions here:
- What does saluton mean alone?
According to PIV, it means:
Ekstera signo de ĝentileco, kiun oni esprimas per vortoj aŭ movoj al renkontata persono
Which roughly translated means:
An external sign of politeness, that you express with words or movements to someone you recognise.
With this meaning, I don’t think there is anything weird about the phrase mi donas al vi saluton, except that if you actually said it it would probably sound very pompous. Just because in English we would say “hello” in the same situation as we would say “saluton” in Esperanto, doesn’t mean they have the same meaning. Perhaps a closer translation of the word in English could be a greeting or a salutation.
- De kio estas “saluton” etimologio?
I would imagine the word has the same etymology as salutation in English. According to the Wiktionary, that comes from the Latin salutatio.