@Robbini
He can kill anything with a thought, so he could probably "Kill" any weapon that he could react to. I wouldn't be surprised if he could kill the poison. That said, I'm wondering:
Would he sense killing intent if you were trying to knock him out specifically to capture him?
Does he have any way of sensing traps, since they shouldn't have killing intent? He'd be vulnerable, relying on his normal senses to react to the trap. Unless he senses the killing intent of the trap-maker, and can kill the trap by reacting to that.
In that case, could he sense natural hazards like lightning, or a landslide, since there should be no intent behind that? Could he do anything about falling from a tall height? Could he "Kill" gravity or something stupid like that?