Is it too masculine?
While I wouldn’t say it sounds particularly feminine to me, it has the same sound as [name]Paige[/name], which has been accepted for girls now. Also, it’s so unusual that I doubt people would be surprised that little [name]Sage[/name] was a girl - it’s different from using an established masculine name, such as [name]James[/name].
I can imagine a very spunky young lady named [name]Sage[/name].
Good luck! [name]Auburn[/name]
I have a little girl cousin named [name]Sage[/name], so it sounds totally feminine to me! 
Apart from my cousin, what I think of is the color and the plant…both of which seem calm but strong, which is certainly something I’d like my daughter to live up to.
[name]Sage[/name] sounds 100% like a girls name to me! I [name]LOVE[/name] it! It reminds me of [name]Jane[/name], which I also love, but with a lot more quirky elements (hard to do in 4 letters!). I can only think of good connotations with this name… Oh, i was wading a book recently where a character has a baby daughter named [name]Sage[/name] and it reminded me how very sweet it is. Yes, I love it! 4 thumbs up!
It’s definitely a girl’s name, [name]IMO[/name].
Not my style since I usually don’t go for word-names. But definitely feminine.