head of the bus seat fan club

A lot of stuff that's considered canon in star wars is actually kind of ascended fanon. Like, if you really dig into it, it's remarkable how much of the lightsaber-juggling, movie-retreading atmosphere of pop culture/the expanded universe Lucas incorporated into the prequel trilogy, likely without realising.

Example: Strictly according to the original trilogy, does Master Yoda possess a lightsaber? I would say no. It is significant that in a film, where every shot is deliberately planned, we never see a lightsaber in relation to Yoda, and the one time he acknowledges Luke's it is dismissively; "Your weapons, you will not need them." By implication, Yoda is a Buddha to Obi-Wan's warrior monk. Yoda is a teacher and a mystic, but he is not a warrior.

Force lightning is another of these things. You go back to the original trilogy, and there's a sense that the Force and what you can do with it is very personalised. Nobody but Palpatine throws lightning, not even his apprentice, and in turn nobody but Vader chokes people to death. Luke does learn the mind trick introduced by Obi-Wan, but that's part and parcel with Luke's growth into a compassionate warrior-philosopher who tries to solve conflicts nonviolently. Force Choke is not 'a dark side force power', it is Vader's power, a manifestation of his crushing authority and smothering presence.

Likewise, Force Lightning is not 'a dark side power', and it is not generic lightning. It is the Emperor's power, characteristic of his cruelty, his sadistic delight in corrupting and hurting other people. We can see this in how it is used. Force Lightning does not split steel or blast people off their feet or blow things up, like a real bolt of lightning - it transfixes Luke in agony, sends him reeling to the floor with torturous pain until he screams for his father's help.

Indigo Bunting (Passerina cyanea) male. Family Cardinalidae, order Passeriformes.