Where did the Warcraft 3 Night Elf hero demon hunters come from?
Had Illidan been training them before he was imprisoned after the Sundering? How could he have because demons were unknown. Was someone else training demon hunters? But why, demons weren't seen for 10,000 years.
Or had Night Elves been practising this form of lite-fel combat for ages anyway, and then the demons arrived and it proved really handy and they learnt more about demons?