Heroes are special dueling swordsmen of the Jianghu. To duel a hero you need to make him spawn. Every NPC carrying a sword can spawning one or more types of heroes including two heroes at the same time.
These are available 24/7. Each type has a special location.
Double heroes have a chance of dropping one or two brocade chests, while single heroes have a very low chance to drop a brocade chest.
Inside that chest is usually a training scroll for the Internal Skill the NPC was using. The level of the scroll is determined by the level of the hero that you defeated, junior, senior, etc. But there is a chance to get a scroll from the chest that does not match their Internal Skill .
Additionally you can can get special treasures when you beat them.