Infusing yang energy, controlling yang energy, channeling yang energy—all of these aren't particularly rare abilities. Most martial artists, or Taoists who walk the path of pure yang, can do it if they have even a moderate level of skill.
The issue, however, is that if they poured such an immense amount of yang energy into a jiangshi, there would be only one outcome:
The jiangshi will dieinstantly.
Only those of the Blazing Sun Sect can manage to empower a jiangshi this way. Because of this unique application of yang energy, this basic technique even has its own name—a distinctive one at that.
Harry, of course, knew none of this. Many things that Vin took as common knowledge were mysteries to him; he probably knew less than even the Blazing Sun Divison's more seasoned field agents.
All he could think about now was how to get through today's funeral without issues, to convince everyone that the jiangshi had been properly cremated and laid to rest.