The special amulet bullet mentioned by Zheng Qing wasn't special due to the method of its creation, but because the talisman used to wrap the bullet was unusual. The talisman used for this bullet was drawn with his own blood.
For most wizards nowadays, using fresh blood to draw symbols is a rare practice.
On one hand, it was dangerous; if the talisman paper did not burn completely and the blood was collected by the enemy, within less than two hours, all sorts of bizarre curses could be bestowed. On the other hand, drawing blood symbols places a tremendous physiological burden on wizards, severe cases even shortening their lifespans.
Therefore, even if fresh blood was used in talismans, it was at most a few drops from the fingertip, followed by crossing another talisman at the end of the drawing session. This is what Zheng Qing had done last semester at Wandering Bar for Li Meng.