Hi to show a line you could edit the raycast script :
add a float value to this line : (float value is the duration it will show the line)
Debug.DrawLine(originPos, originPos + dirVector * debugRayLength, debugColor.Value);
this will show line for 3 seconds
Debug.DrawLine(originPos, originPos + dirVector * debugRayLength, debugColor.Value, 3.0f);
on the video i do not think it is 'curving a raycast' on the blade there are several short raycasts and due to the drawline delay it looks like its a curve.