I don't really know much about Fairy attacks... but "Moonblast" sounds amazing.
Following the pattern set by the other eevee evolutions, it is either the fairy equivalent of thunder and fire blast or the fairy equivalent of water gun and razor leaf. I am inclined to believe the former.
The surest way not to lose is to not play, but where's the fun in that? If words are power, you'd think that dictionaries would be more interesting.