I am a huge fan of Ars Magica, but while it certainly creates very capable mages from the beginning - I think the OP would be disappointed with the role of warriors in the game. There are not a ton of combat options for non-mages. I would play or run Ars in a New York second with the right group - but it is not a game with a ton of tactical combat options.I'll also recommend HERO system. But I always do in these threads.
Ars Magica is another awesome game. Haven't played it in years unfortunately, hard to find people who are keen to try and master the magic system, which is admittedly complex. But consistent! The game play is actually really simple (even magic once you get the hang of it.)
Using the criteria of the OP I think 13th Age is a better fit.