In my opinion, only a small handful of the Blue Magicks are useful. Frog Drop is generally useless for me, because by the time I get it, I'm a super high level and have the Gastro Fork so will hit high enough anyway. Really, I only use White Wind. 25% of Quina's max health on a high level is plenty of healing, especially when you consider it is for the whole party.

Like I said though, I'm a bit of an over-leveller, so my party can easily beat Necron with just Amarant as a healer.