Beat butter at medium speed with an electric mixer until creamy; gradually add 1 1/2 cups sugar, beating well. Add eggs, 1 at a time, beating until blended after each addition. Stir in banana and vanilla.
Combine flour and next 3 ingredients; add to butter mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed until blended after each addition.
Combine pecans, 2 tablespoons sugar, and cinnamon. Pour half of batter into a greased and floured 12-cup Bundt pan; sprinkle with pecan mixture. Pour remaining batter over pecan layer. Bake at 350° for 50 minutes or until a long wooden pick inserted in center comes out clean. Cool in pan on a wire rack 10 minutes; remove from pan, and cool on wire rack.
Combine powdered sugar and water, stirring until smooth. Spoon glaze over cooled cake.