I don't know much about knives, so I'll let others answer your last question.
As for the law, first be sure you don't run afoul of this one:
76-10-509. Possession of dangerous weapon by minor.
(1) A minor under 18 years of age may not possess a dangerous weapon unless he:
(a) has the permission of his parent or guardian to have the weapon; or
(b) is accompanied by a parent or guardian while he has the weapon in his possession.
(2) Any minor under 14 years of age in possession of a dangerous weapon shall be accompanied by a responsible adult.
You must have parental permission, and it would be a really good idea to have it on you, in writing. Just in case.
Also, you should obviously be sure not to carry in a school zone. That means within 1000 feet of any school property or any school-sponsored event. When you start drawing thousand-foot circles around all the school properties, you find that this is a pretty big restriction.
As you mentioned, you should also be careful not to conceal your knife. Not if it's a "dangerous weapon", anyway. What is a "dangerous weapon"?
(6) (a) "Dangerous weapon" means any item that in the manner of its use or intended use is capable of causing death or serious bodily injury.
(b) The following factors shall be used in determining whether a knife, or any other item, object, or thing not commonly known as a dangerous weapon is a dangerous weapon:
(i) the character of the instrument, object, or thing;
(ii) the character of the wound produced, if any;
(iii) the manner in which the instrument, object, or thing was used; and
(iv) the other lawful purposes for which the instrument, object, or thing may be used.
Clearly, even a small pocketknife can cause death or serious injury, but its "intended use" is as a tool, not to cause harm. Fixed-blade knives, like hunting knives, are more of a gray area and things like punch daggers clearly serve no purpose except as a weapon. You could use them as a tool for, say, opening boxes, but they're clearly not intended for that use, and would be clumsy in that role.
So unless your knife is clearly a tool, not a weapon, don't conceal it.
Also, be very, very careful about how you use your knife. Threatening someone with it is a serious crime -- a felony -- unless in response to a similarly-deadly threat from them.
Finally, if you're openly carrying a knife, you should try very, very hard to avoid any sort of encounter that might turn the slightest bit violent. Why? Because the presence of your knife could escalate that encounter to deadly force levels and depending on the circumstances YOU could be the one held liable for that. It could seriously ruin the rest of your life.
I'm not trying to discourage you, but the fact is that most minors (and many adults) aren't accustomed to thinking really hard, and very seriously, about the possible worst-case outcomes of their actions and decisions. When it comes to deadly weapons, failing to really think through the issues and understand the potential results can land you in a world of hurt, the kind that destroys every idea you ever had about your future.
Be careful out there.
Four boxes protect our liberty: soap, ballot, jury and ammo. Use in that order.
Utah CFP Instructor; NRA Certified Instructor for Pistol, Rifle and Self-Defense in the Home; NRA RSO.
I am not a lawyer!