I know nothing about harp playing, but a lot about frailing. Bonny Shaljean says "just take a look at the harpers' hands in the many engravings and drawings that exist. When do you ever see the palms facing away from the strings?". If you frail, the palm does NOT face away from the strings. However, she's right about the difficulty with complex melodies. On the banjo these use extra notes which are achieved by "hammering on" or "pulling off" - there's no way this can be done on the harp, where the strings aren't fretted.
Cheers
Ray