Was feces (tetanus) the most powerful poison in the Sengoku period? Was it used to coat arrowheads in battles?

"What do you think was the strongest poison in the Sengoku period?" My editor suddenly asked me this question. Poisons are not only used in the Sengoku period, but are often used in assassinations and murders. It is true that in modern times there are a wide variety of chemicals, but in the Middle Ages they had to be produced from nature, and it must have been very difficult to test their effectiveness. So, realistically speaking, what could hav…