Cultivation Is Easy?

Taken in as the three immortal masters' junior uncle, he spends ten years trapped in a mystical diagram with nothing to show for it. Once free, a casual gesture shatters the barrier guarding their sects. He masters 108,000 sword moves in two hours and helps another cultivator break through. Yet spiritual energy flees whenever he tries to absorb it. Just as he finds hope in physical training, one master's sword falls over the eastern sea. What happened to the three masters?