You can view the animatable properties of animation layers themselves (such as Weight) in the Time Slider, Graph Editor, or Dope Sheet.
To set up these animation editors to show the weight animation for a selected layer, do the following:
To view the layer’s Weight animation in the Time Slider
The Weight keys for the animation layer display in the Time Slider.
To view the layer’s Weight animation in the Graph Editor
Curves for the layer’s Weight display.
To view the layer’s Weight animation in the Dope Sheet