Seems that lethal dose for arsenic is likely too high to be transmitted by even a pure arsenic trioxide blade, unless it was manufactured with the intent of leaving bits inside the wound, like maybe a blade a rough brittle surface to leave grit. Even so, would have to introduce ~50+mgs worth, which sees like a tall order.

Seems arsenic bronze is even less toxic, so probably not poisoning anyone. I wonder if the minor local toxicity of arsenic blade cuts would reduce the chance of the wound causing sepsis.