Preheat oven to 300 degrees.
Mix sugars, salt, cayenne, and cinnamon, making sure there are no lumps; set aside.
Beat egg white and water until frothy but not stiff.
Add walnuts, and stir to coat evenly.
Sprinkle nuts with sugar mixture, and toss until evenly coated.
Spread sugared nuts in a single layer on a cookie sheet fitted with parchment paper.
Bake for 30 minutes, stirring occasionally.
Remove from oven, and separate nuts as they cool.
When completely cool, pour the nuts into a bowl, breaking up any that stick together.