Rhode Island - 11-47-42. Weapons other than firearms
   prohibited. (A) No person shall... with intent to use the
   same unlawfully against another, carry or possess a
   dagger, dirk, stiletto, sword-in-cane, bowie knife... nor
   shall any person wear or carry concealed upon his person,
   any of the aforesaid instruments or weapons, or any razor,
   or knife of any description having a blade of more than
   three (3) inches in length measuring from the end of the
   handle where the blade is attached... (B) No person shall
   sell to a person under eighteen (18) years of age, without
   the written authorization of the minor's parent or legal
   guardian, any [of the above]
- 11-47-43. Collectors... exempt from section 11-47-42. The
   provisions of section 11-47-42, so far as they forbid the
   possession of certain instruments or weapons, shall not
   apply to any person who possesses or is making a
   collection of the same as curios, or for educational,
   professional, scientific, or any other lawful purpose,
   without intent to use any such instrument or weapon
   unlawfully...
- 11-47-48. No person, firm, or corporation shall display in
   a place of business by means of a window display any...
   firearm... or any dagger, dirk, bowie knife, stiletto...
- 11-47-59. No person shall commit or attempt to commit any
   crime of violence while having in his or her possession a
   knife with a blade more than 3 inches long...


http://www.knife-expert.com