The Smoothing tab allows you to smooth the entire mesh weights, or select points, interactively.
Sets the amount of smoothing to apply to the object or selected points.
Defines how much spread you want to apply when smoothing the weights. The higher the value, the more diluted over distance the weights will be.
This curve defines the shape of the falloff over the set distance. The left of the curve represents the starting point of the weights, the higher the curve is, the stronger the weight value.
Applies the smooth command to the whole object or selected points
When this option is enabled, the impact of the Falloff curve on the weights can be seen interactively in the viewport once the Smooth command has been applied.