I have only been studying Attic Greek for a week now, so I can’t claim to be an expert:) but I am working on a Master’s degree in linguistics, for whatever that’s worth (sometimes I wonder:)) But to me, putting a masculine ending on a feminine word to make it a male name sounds like the most natural thing in the world. I have really been confused about what all the fuss is about. The phenomenon is very common in names in many modern languages, as others have pointed out.
Moving on, I did a quick Google search on your question and have listed links above to some sites that describe Greek naming conventions. As you will be able to see if you peruse them, many ancient Greek names have both masculine and feminine versions, being derived originally from a noun that was either one gender or the other (actually one of three genders). I have cut and pasted one example from the top website listed above for your immediate gratification. As you can see, in a word like, “NIKE” the “E” is the feminine nominative singular ending. So in Greek, “victory” is a feminine noun. However, the Greeks seemed to have no problem deriving a masculine name, “NIKIAS” from it.
Usage: Greek Mythology, Ancient Greek
Other Scripts: Νικη (Ancient Greek)
Means “victory” in Greek. Nike was the Greek goddess of victory.
Usage: Ancient Greek
Other Scripts: Νικιας (Ancient Greek)
Derived from Greek νικη (nike) meaning “victory”. This was the name of an Athenian general who fought in the Peloponnesian war.
See also PELAGIUS, PELAGIA; AGAPE, AGAPIOS; CHRYSANTHE, CHRYSANTHOS; etc.
I have restricted the examples listed above to names based off nouns. Many Greek names are derived from adjectives as well. However, in Greek, adjectives are declined to match the gender of the noun they are modifying, so most adjectives have masculine, feminine, and neuter forms (unlike nouns, which are usually one gender). Some nouns do have both masculine and feminine forms though. In my meager exposure to Greek thus far, I have learned the word DOULOS, which means “slave,” (referring to a male). The -OS ending is the masculine nominative singular. In the course of doing my Greek homework today, I encountered the feminine equivalent DOULE, with the feminine -E ending, like in NIKE above, meaning “female slave.”
So yeah, in conclusion, I would think the practice of changing a word’s grammatical gender to match the actual gender of the person whose name was derived from that word, would be fairly common and natural. Of course I am open to dissent, if any Greek experts have any differing views. I can poll some of my more learned Classicist friends in the matter, but I wanted to contribute what little I could. Hope this helps!