Amon and Energybending.

He is probably blocking the charkas.... because to energybend someone, your soul must be stronger than the other's. I think Lin Beifong has a stronger soul since she sacrificed herself to save the remaining Airbenders and Amon has been doing evil so if he was really energybending he would have corrypted his soul a long time ago also Amon can't bend any of the elements so there is no energy within him to be able to overtake someone elses sould with.