>> From Old French given name Milo, of problematic origin, possibly from an unknown Germanic element, or a short form of Slavic names beginning with mil- "grace, favor". The English form is associated by folk etymology with Latin mīles ("soldier").
It would be nice to know that the Old French name didn't secretly happen to match the hypothetical Old French form of the Latin word for soldier. I sadly don't personally know how to check what form miles, militis would have taken in Old French.
A good heuristic, though, is that if the French name had come from this very common Latin word, someone would have already thought of that (as has in fact happened many times) and it would have been thoroughly investigated. The evidence in support must be somewhere between "wafer-thin" and "robustly contradicted by the known sound changes from Latin to French".
It isn't!
https://en.wiktionary.org/wiki/Miles
>> From Old French given name Milo, of problematic origin, possibly from an unknown Germanic element, or a short form of Slavic names beginning with mil- "grace, favor". The English form is associated by folk etymology with Latin mīles ("soldier").
It would be nice to know that the Old French name didn't secretly happen to match the hypothetical Old French form of the Latin word for soldier. I sadly don't personally know how to check what form miles, militis would have taken in Old French.
A good heuristic, though, is that if the French name had come from this very common Latin word, someone would have already thought of that (as has in fact happened many times) and it would have been thoroughly investigated. The evidence in support must be somewhere between "wafer-thin" and "robustly contradicted by the known sound changes from Latin to French".