The thing that sets Legendary weapons aside from any other rarity are the titles. I posted up a while back a list of all titles and prefixes for guns and what they mean. The "Legendary Titles" are exclusive to the orange rank of weapons. These titles generally have pretty awesome effects and have the potential to be more badass than any other weapon around. Obviously this is not always the case but it is more likely to happen.
The thing that sets Legendary weapons aside from any other rarity are the titles. I posted up a while back a list of all titles and prefixes for guns and what they mean. The "Legendary Titles" are exclusive to the orange rank of weapons. These titles generally have pretty awesome effects and have the potential to be more badass than any other weapon around. Obviously this is not always the case but it is more likely to happen.