Vantage is really only useful on tankier units and distant counter types. My Minerva had vantage early on, but she rarely utilize it because at lvl 40 Arena everyone is build for OHKO.
I find that "Breaker skills" is the most safe skill to pass on. I really don't know what to put in Cherche since I'm not raising her, but this is how my Minerva is build
She has
-Swap, a pseudo +1 move as long as she can swap with units 1 space ahead of her move range, good for body blocking
-Moonbow Special, with only 1 action cooldown since she has Hautclere that reduces 1 action cool down
-Lance Breaker, so she can dominate even the tankiest of Effies.
I just see this as a basic guide
http://feheroes.wiki/Skills_Table