I bought both the "Greater Lightning Rune Arm" and then the "Lightning Rune Arm" from the DDO Store hoping they would be improved versions of my favourite rune arm so far, Flicker. Unfortunately, rather than the ball lightning style "Electrical Lash" of Flicker, they are instead the short range style "Electrical Blast" of Chimera's Breath. While this is bad news for me, it may be good news or at least helpful news for others. Also, the higher charges do indeed seem to have a larger range (the animation certainly does).

Screenshots of the rune arms: