I see no contradiction. I also did not score well in language skills in school.
I interpret the law as saying that there are two classes of weapons, "offensive weapons" and "dangerous weapons". Offensive weapons as defined in Iowa code are generally banned, one does not simply obtain a license to own or carry them. Offensive weapons are things like machine guns and artillery, where possession is limited to agents of the government.
I understand that Iowa Code breaks down the "dangerous weapons" category into three sub-categories. There are firearms, specified dangerous weapons, and non-specified dangerous weapons. Firearms in Iowa Code is similar to the definition in federal law but not identical. For example federal law does not consider a cap and ball revolver as a firearm but Iowa Code does. Iowa Code does have some "dangerous weapons" specified explicitly, such as knives of a certain size and nature, billy clubs, and I believe stun guns and pepper spray falls in here too. Iowa Code allows for anything used as a dangerous weapon to be considered a dangerous weapon. Use of a rock, baseball bat, ball peen hammer, length of 2x4, or a pry bar as a bludgeon will get a person a dangerous weapons charge. I recall someone charged with using a pickup truck as a dangerous weapon.
Carrying a firearm openly outside of city limits does not require a permit. Carrying a firearm openly or concealed in city limits requires a permit.
Carrying a dangerous weapon concealed requires a permit. Openly carrying a dangerous weapon, that is not a firearm, is permissible inside or outside city limits without a permit.
Where I get confused is if someone can be charged with carrying a concealed weapon if they happen to use something in their pocket, like car keys, as an improvised weapon. Technically it was concealed on the person but it did not become a dangerous weapon until revealed and used to jab out someone's eye. As Darkshadow62988 points out this is likely something to be argued before a judge.
