you see, the good doctor has a bunch of points in kataleptic toxicology, but he put most of them into the "make esoteric medicines" tree, with a side of "metabolize any poison" for funsies. he had none left over for the actual "make poisons to kill people" tree
that being said, the esoteric medicine tree DOES have some handy offensive utility traits, like "make very very effective paralytic drugs"
Wren (Lady Lemures) knows a lot more about making poisons to kill humans in specific ways than you might expect for a person whose profession involves hunting beasts rather than humans. the doctor always jumps at the chance to, er, sample one of her creations. for funsies.
(fallen london stamps by