In a sense, from the very beginning of the battle, the Elderly had been "feeding" He Ao moves, demonstrating those skills for him to see.
Of course, if he hadn't learned those skills, or if his strength wasn't enough, he also believed the Elderly wouldn't hesitate to kill him.
During the entire battle, the Elderly actually held nothing back. A moment's distraction from He Ao would have been met with immediate death.
He was treated specially, but not entirely so.
If he learned, that was He Ao's own skill. If he didn't, then the next capable person would take his place.
However, this Elderly had long been dead; what stood before him was nothing more than a metamorphosed Evil Spirit created by the Relic of the Bygone Days.
The "duty" he adhered to was also completely "metamorphosed and distorted."
He Ao extended his hand and grasped the hilt of the Broad Sword.