Soul Fury (4e Feat)
From D&D Wiki
Allows your unarmed attacks to deal an elemental type of damage, and treats your unarmed strikes as High Crit weapons.
Benefit: When you choose this feat choose cold, fire, lightning, necrotic, poison, radiant, or thunder. When making a basic attack with your hands as either a weapon or implement, the damage you deal is of your chosen damage type. In addition, when you strike with your hands as a weapon, they are treated as High Crit weapons.