I disagree about the torch. Lightening as itself gives out very little light, it has only light of it own. The Devil's torch is indeed the light of the truth. The Devil is known as the adversary, the obstacle that we must overcome in order to move on. What better object is there to bring all our hidden desires and fears to light than the torch, the flame that lights up the truth?
Edited to correct grammar and spelling (I was kind of on the drunk side) and to add this:
While the fire may burn and singe us a little in the end it is truly all for the best. For example. in the RWS clone, the Morgan-greer, the light is only a small candle, that gives off an eery geen light, that feels stagnant and full of malaise, which, to me, means something else entirely. The Morgan-Greer Devil is the fear of the dark, of the unknown, fear of fear itself, and ultimately, fear of what you can be, should you decide to rid yourself of that fear, blow out the candle and go into the sunlight.