Place pecans and almonds in a large bowl; stir in 1 cup sugar and 4 cups warm water. Let stand 10 minutes. Drain well; return to bowl. Pour butter over nuts, stirring to coat.
Stir together remaining 1/2 cup sugar, chili powder, and next 4 ingredients; pour over nut mixture, tossing to coat. Spread in a single layer on a 15- x 10-inch jellyroll pan.
Bake at 350° for 30 to 35 minutes, stirring occasionally. Arrange in a single layer on wax paper, and let cool. Store in an airtight container.