Add “edit_theme_options” capability to the “editor” role:
1) Open “Users->User Role Editor”, select “Editor” role.
2) Turn ON checkbox for the “edit_theme_options” capability, click “Update”.

After that user with “Editor” role will receive access to the full “Appearance” menu, as all its submenu items are protected by the same “edit_theme_options” capability.
If you wish to allow to the ‘editor’ role to work just with “Menu” and “Widgets” items of the “Appearance” menu, you need to block other items with “Admin Menu Access” add-on.