There is no magic "SW2XL.exe" made by Koei. Accepting this is the first step to playing the game safely.
Originally released for the PlayStation 2 (and later ported to PlayStation 3 and Xbox 360 as part of the Samurai Warriors 2 with Xtreme Legends bundle), this expansion added a mountain of content: new characters (such as the fan-favorite Kojiro Sasaki), new story modes, a difficult "Survival" mode, and the brutal "Xtreme" difficulty setting.