With v2.5 of the Ghostly Undead list, one can take the Ghost Knight for 45 points, base cost, and the Ancient Wraith for 55 points, base cost. They both have the same 4+/6+ Quality and Defense, and they both have the same special rules of Ethereal, Hero, Strider, Tough(3), Undead.
However, the Ghost Knight can take a +5 point upgrade of a Great Weapon (A3, AP(2)), effectively making him the same exact unit as the Ancient Wraith, but for only 50 points (and with additional customization options).
Am I missing something that would drive me to use the Ancient Wraith, versus just making an equivalent unit with the Ghost Knight?
I like my tea, as I like my nights: dark, endless, and impossible through which to sleep.