What do we know about energy bending and does it play a role in the new Avatar, Legend of Korra?
My theory is yes, it does. Some peole say Amon has developed his own technique to take away bending perminatly, but i do not believe this is the case at all. I believe Amon has somehow stumbled upon away on how to energy bend. As stated in the Avatar history books, energy bending was once the only form of bending available to all humans. Furthermore, it was before the time of the Avatar, hence why it has become an almost forgotten art (The Lion Turtle was the last to know of its power and used his energy bending to pass on his knowledge of energy bending to Aang). When bending of the elements was discovered is when the Avatar arose, we know this much. And with that, energy bending was almost lost forever.
What does this have to do with relation to Amon. Well directly we can't prove anything, but we have seen flashbacks from Korra. These flashbacks show Aang fighting someone from the past, and possibly taking his bending away using the energy bending technique. Could this possibly be a young Amon fighting Aang, or could it possibly be that mysterious man's son?
Point is, know one really does know until all is revealed. But there are plenty of options, and it is great for us as viewers to let our creative minds come to form and reveal fantale stories of what could be!
With all this information in mind, and what i have discussed. Is it possible Aang has left the secrets of energy bending with the mysterious man, of which who he took his bending powers away from. In doing so passing the secrets of energy bending on accidently? Anythings possible people, and we have learned this from viewing the Last Airbender a 1000 times!!! One of my many theories is, is that it could also be that mans son. As it is stated, a broken spirit wanting to energy bend will be overcome by its power. This leads me to think the man has passed on the knowledge he learned from Aang to his son, and is seeking revenge in his fathers name. His spirit isn't broken and he has a driving purpose that will give him the power to control the energy bending.
Just a theory as Korra has had two or three visions of Aang fighting this man now/standing in trial with him too.