I'll try to keep this concise and too the point.
It is illegal to possess (even in the home) switchblades or belt-buckle knives.
It is illegal to
carry concealed any "Dirk, dagger or machete."
Seriously, that's it for state law. By implication, that basically means you can
open carry anything ya darn please so long as it's not a switchblade or belt-buckle knife (which are pretty rare). As for "Dirk, dagger or machete" that almost always means fixed blade knives, making folders legal to carry concealed. There are no length provisions; a knife is legal based on it's style and type, not it's size. A 1" dagger blade neck knife is illegal if concealed, legal if open carried. Intent also plays a part. In
Knight v. State 2000, the defendant was convicted of a concealed weapon for carrying a 4" steak knife, because it was clear by his kicking down someone's door and cutting them with it that he had intent to use it as a weapon.
Source:
http://leg.state.nv.us/NRS/NRS-202.html#NRS202Sec350
Washoe County basically just echos state law, adding nothing of notable difference except for it is illegal to conceal a "dangerous knife." However, that term was ruled as unconstitutionally vague in
Bradvica v. State 1988, and while the state law above removed it long ago, Washoe never updated it's statutory language. Basically, that means that while the law still says "dangerous knife," it would not hold weight in court.
http://www.washoecounty.us/clerks/files/pdfs/county_code/Chapter050.pdf (see 50.075)
Reno, I don't see anything about knife carry, though the potentially relevant statutes are "reserved."
http://library.municode.com/HTML/14160/level3/P2_T8_C8.18.html
Sparks only seems to have laws on brandishing weapons "in a rude, angry or threatening manner" "except in self defense."
http://www.ci.sparks.nv.us/governing/muni_code/Title_9/63/020.php