“And the children of Israel went up armed out of the land of Egypt, and Moses took the bones of Joseph with him…” (Exodus 13:18-19)
What were the weapons that the Israelites took with them? Rabbi Moshe Meiselman, nephew and student of Rabbi Joseph B. Soloveitchik, teaches that the armament was comprised of the bones of Joseph. The merit of a righteous person whose attributes become yours serves as a shield for you. The Hebrew for bones is atzmot. The Hebrew for (good) character traits is atzimut. We can then interpret the verse to mean that Moses took with him the good qualities of Joseph, learning from Joseph’s example how to lead a people and protect them.