The park authority have two distinct groups; scouts and guides. Scouts are local men. Guides are more educated people who have knowledge of the fauna and flora and who speak English. At present it is a park rule that a scout has to go with the group into the park. The reason is as much to make local employment than for your safety because it is difficult to get lost in the Simiens and the trek is very secure. There is no danger from wild animals in the park. The carrying of guns by the scouts is a throwback to the early days when they looked to other African parks for standards to apply. Consequently Scouts do carry guns (kalashnikoffs) which may disturb some tourists. Professionals in the tourist industry work hard to dispell the myth of a land of war and famine so this is a contradiction. If you don't like the gun then just ask the scout to keep a discrete distance. However these guys are very friendly and they can provide good information through an interepreter because their english is poor. Historically it was not essential to take a guide although your trip will be more informative if you do.