Not much is known about Violet Evergarden, aside from the fact that she possesses ridiculous physical strength, well beyond that of a normal human being. This could be handwaved as being due to her prosthetics, but even if that was the case, lifting another person or a heavy suitcase would still put a lot of strain on her back and shoulder, and wearing high heels while carrying said suitcase would only cause even more trouble. However, in chapter 10, "The Demigod and the Auto-Memories Doll", a cult claims that the gods are real, and that demigods exist, who are supposedly children of said gods and normal humans. Demigods supposedly possess certain qualities that exceed that of normal humans, such as extreme intelligence or charisma. Considering Violet's mysterious past, her ridiculous strength and her appearance constantly being described as angelic or mature beyond her years, and the fact that Violet, Lady Lux, and Sister Lisbon all agree that Violet looks completely like the goddess of war, Garnet Spear, it is not unlikely that the cultists are actually right, and that Violet is actually a demigod.
In episodes 1-7 of the Anime, lots of work is put into making even irrelevant background characters look unique. In the flashbacks in episode 8, however, all the soldiers look alike, except Violet, Gilbert and Hodgins (the only two soldiers to actually treat her like a human being). At first, this seems a bit jarring, considering the level of detail put into the previous episodes, but it makes perfect sense, since Violet only cared about Gilbert and the flashback is Violet thinking back on the war. In other words, the reason the soldiers all look the same is that, to her, they were all just the same.
In the Gaiden volume's final chapter, the streets of Leiden erupt into battle between the CH Postal Company and the Salvatore Postal Company. It should be no surprise that with both companies having been founded by war veterans (Claudia Hodgins and Salvatore Rinaudo, respectively), it turns out many of their employees are also former soldiers, and have access to military weaponry. One notable real life example of a similarly heavily armed postal service is the United States Postal Service, which has a long history of being armed through the United States Postal Inspection Service (which is the oldest federal law enforcement agency in the country, commissioned on August 7, 1775), and in the aftermath of World War I, the USPS even used U.S. Marines as security and the PIS bought the mighty Tommy Gun in significant numbers.
How do the other Auto-Memories Doll other than Violet protect themselves when they are in the field? While Violet is a ex-Child Soldier and a Walking Armory, the rest of them seem to be average civilian women without any notable self-defense techniques. Yes these women seemingly do their work at the office but what happens to them if they are called out to do fieldwork? Do they screen their clients? Erica starts to shut down when a client starts to yell at her. Cattleya is very beautiful and famous. Considering real life, do they have protection from potential stalkers, rapists or human traffickers? Do they have any sort of guarantee for their safety since Auto-Memory Dolls seem to employ educated and very good-looking young women?
The simple answer is they protect themselves the same way thousands of average people who conceal carry do. Benedict also carries a handgun for protection in Chapter 9, so it can safely be assumed CH Postal's other amanuenses do the same when traveling. Something like a snubnose revolver or a compact semi-auto can be used by practically anyone with less than an hour of familiarization, and producing a weapon is enough to make a would-be criminal think twice about his choice of prey.
and the PIS bought the mighty Tommy Gun in significant numbers.