Or alternatively, have ijkl serve 75% weight and esdf serve 25% weight. Then you can achieve 100%, 75%, 50%, and 25% combinations using both hands.

    Left | Right | Total
   ------|-------|------
   +0.25 | +0.75 | +1.00
    0.00 | +0.75 | +0.75
   -0.25 | +0.75 | +0.50
   +0.25 |  0.00 | +0.25
    0.00 |  0.00 |  0.00
   -0.25 |  0.00 | -0.25
   +0.25 | -0.75 | -0.50
    0.00 | -0.75 | -0.75
   -0.25 | -0.75 | -1.00

(two ternary digits -> 3^2 = 9 combinations)