The Deviljho long sword isn't that good. If memory serves it needs the awaking skill and the dragon element isn't that high. Ice works best versus Alatreon except when it is flying then Dragon is best but it is kinda hard to hit it consistantly in the air.Out of the Deviljho weapons the Hammer and Great sword are the best to get.For the other weapons it is best to get the Alatreon sword and shield,switchaxe,Lance,and long sword.