You "Knead" the Eraser Tool
An eraser has always been part of the artist's toolbox; digital art is no exception. Choosing the Eraser tool (E) with a soft-edged, round brush and lowering the Opacity in the Options Bar is similar to using a kneaded eraser to soften hard edges and enhance blends and highlights. Additional eraser tip: In Photoshop, any brush can become an eraser by choosing Clear from the Mode drop-down menu in the Options Bar.