If the Emperor's hands were amputated, would he still be able to shoot lightning? What about if his arms were completely removed?
Note: I am looking for a canon-based answer.
As seen in this question, channelling1 Force lightning isn't dependent on having hands. @Richard even found a picture (from Star Wars: Legacy #005) of a Force user channelling Force lightning from their entire body:
1 Yes, I'm using Wheel of Time terminology to answer a Star Wars question. So sue me.