Am I allowed to carry a handgun or mace/pepper spray in an area/community that does not have an Eruv, yet is clearly dangerous for yidden to be walking around in, and out of fear of being attacked G-d forbid by groups of people that have started up and attacked Jews? Thank You.
No, this would not be permitted. While for danger there is room for some leniency, in this case one could avoid the danger by staying home at dangerous times, walking in safe areas, in groups etc.. If the place you live in is not a Rshus Harabim, but could be classified as a Karmelis [a domain prohibited to carry in by Rabbinic decree], and the situation was impossible without carrying something [i.e. the above solutions are not viable], there would be room for leniency to carry some protective gear in an abnormal way [i.e. under one’s hat]. This would constitute a situation of 2 leniencies [karmelis and shinui] for which one could justify carrying for a mitzvah, such as going to shul.
See Rama O:C 301:33, Shu”t Tzitz Eliezer Vol. 13:34, Shmiras Shabbas Khikchisa 40:7, SHu”t Mishneh Halachos Vol 7:56.