Have you noticed this little gem yet?
Basically:
- Select a Fascia – the tool is revealed
- Click Modify Mitering
- Choose the option you want
- Click a fascia edge
Various options are available:
Vertical miter
Horizontal miter
Perpendicular miter
You can learn more at:
Changing Mitering Options for Roof Fascia – WikiHelp
Its in 2012 too