I don’t agree with your definition. You do not have to be called a sciencist to be have a career in a “hard science”.
It isn’t that one type of science is more rigorous or challenging than the other. For example, while you may consider chemistry harder to understand than anthropology, that does not have anything to do with chemistry being considered a hard science and anthropology being a soft science. Rather, it has to do with experimental design and the scientific method. Hard science involves experiments where it is relatively easy to set up controlled variables and make objective measurements. Particularly in sciences dealing with people, it may be difficult to isolate all the variables that may influence an outcome. In some cases, controlling the variable may even alter the results! Simply put, it is harder to devise an experiment in a soft science.
http://chemistry.about.com/b/2014/02/14/difference-between-hard-science-and-soft-science.htm
Engineering is not a science. Engineers are certified to design, build, or maintain things. Scientists study things by using observations and hypothesis-driven experimentation. These are very different functions, and this is clearly evident by the different methods of training and certification in these fields. While engineers and scientists may use similar tools, such as mathematics and statistics, that doesn’t mean an engineer is at all qualified to be a scientist or that a scientist is qualified to design or build something. There are some individuals who do have the training and qualifications to work in both fields, and these people will agree that an engineer is not a scientist, and certainly not a hard scientist.