To Blend Edges Using a Variable Radius

Select the Blend Feature tool.
The Blend Feature tool settings window opens.
Set Blend to Edge Variable.
Enter values for Start Radius and End Radius.
Note: The Start Radius will be at the end nearest to where you select the edge.
Enter other settings as required.
Select an edge to blend.
The selected edge highlights.
(Optional) To select additional edges, hold <Ctrl> and enter data points to select edges.
Accept to blend the edge(s).
The blended edges displays.

Tip: Edges that are blended in the same operation are modified as one feature when they are modified with the Modify Solid or Feature tool.
Accept or reject the blend.

Blending an edge. Left: Identifying the edge (1). | Right: The resulting blended edge.