Iowa - Crime Control and Criminal Acts - Definitions. 702.7.
   Dangerous weapon. A "dangerous weapon" is any instrument
   or device designed primarily for use in inflicting death
   or injury upon a human being or animal... Dangerous
   weapons include, but are not limited to, any offensive
   weapon... firearm, dagger, razor, stiletto, switchblade
   knife, or knife having a blade exceeding five inches in
   length.
 - 724.4. Carrying weapons.
1. Except as provided in this section, a person who goes
   armed with a dangerous weapon concealed on or about the
   person... commits an aggravated misdemeanor.
2. A person who goes armed with a knife concealed on or about
   the person, if the person uses the knife in the commission
   of a crime, commits an aggravated misdemeanor.
3. A person who goes armed with a knife concealed on or about
   the person, if the person does not use the knife in the
   commission of a crime:
a. If the knife has a blade exceeding eight inches in length,
   commits an aggravated misdemeanor.
b. If the knife has a blade exceeding five inches in length
   but not exceeding eight inches in length, commits a
   serious misdemeanor.
4. Subsections 1 through 3 do not apply to any of the
   following:
a. A person who goes armed with a dangerous weapon in the
   person's own dwelling or place of business...
b-d. [officials]
h. A person who carries a knife used in hunting or fishing,
   while actually engaged in lawful hunting or fishing.
i. [valid permit]
- 724.1. Offensive Weapons... 5. A ballistic knife. A
   ballistic knife is a knife with a detachable blade which
   is propelled by a spring-operated mechanism, elastic
   material, or compressed gas... Section 724.3. Any
   person... who knowingly possesses an offensive weapon
   commits a class "D" felony... (Also see Section 724.4.
   carrying weapons.)

  Iowa Case Law:
- "Intent was essential element in determining whether
   defendant who was found in possession of ten-inch kitchen
   knife was guilty of crime of carrying a concealed weapon."
   (1974)
- "Defendant, who was found carrying two pocketknives, one in
   pocket and one on chain around his neck under his shirt,
   could not be convicted of carrying concealed dangerous
   weapons without proof of intent to use knives as weapons."
   (1966)
- "Intended illegal use of knife cannot be inferred from
   defendant's bad reputation or former convictions for
   assault." (1966)
- "Actual intent of user is not the issue in deciding whether
   instrument or device is dangerous..." (1984)