Or is it that, for example, bacteriological weapons is the creation of engineers only?
Yes, engineers. When it comes to invention and application, it is the engineer's job. Studying and researching itself is not evil, it's rather neutral; it's the application that has the potential for malevolence.
I'd say that if you want to look into ethical problems within science, it could be something related to the methodology. Like experimenting with animals or experimenting with humans in a harmful way and without consent. That has been seen throughout history, like the dogs subjected to dual-head transplantation or the chimp that got his head removed and transplanted to another body or the individuals who served as test subjects in syphilis research and so on.