You might check out the Aria Forte, which a number of pro harpists I know use.
The light is strong all the way to the bottom of the page while not being too bright on top. I like that it keeps the light out of the audience’s eyes. Its rechargeable through USB and runs for 8 or more hours on full brightness. You can choose whatever brightness you like with the dimmer knob, too.
http://www.arialights.com