The relevant parts of the law are these:
Any person, other than one of the following, who carries a concealed and dangerous weapon is guilty of a Class A misdemeanor
Source - 941.23(2)
The exceptions are if you are or were a cop, if you are in your own home or place of business, or if you have a concealed weapon license.
In the cast of the latter two exceptions, the weapon must be one of the following:
"Weapon" means a handgun, an electric weapon, as defined in s. 941.295 (1c) (a), a knife other than a switchblade knife under s. 941.24, or a billy club.
Source: 175.60(1)(j)
Putting it all together in plain English:
If you are not a cop, not on your own land, don't have a concealed weapon permit
and you are carrying any kind of non-automatic knife concealed, it is a judgement call that must be made by that police officer, and if arrested, another judgement call that must be made by the judge and jury. Case law indicates it is the totality of the circumstances where the knife is found, what the apparent or expressed intent of the knife carry was, and the design of the knife being primarily intended as a weapon.
Given the worrisome uncertainly of legality, I would advise against carry of a knife for you as a minor living in Wisconsin. You don't have to listen to me, you can do as you please, but when you add in a few other factors too it really does not sound like a sound defense strategy. Here's some things to consider. Say you had a knife when you were being robbed. Here's the most likely outcomes according to crime statistics if you use the knife to defend yourself:
1. Robber is using a gun. You die.
2. Robber is using a knife. You both die.
3. Robber is unarmed and you stab them. They die, you go to jail for excessive force.
A knife only does two things reliably: scare and kill. If you are putting blade to flesh, plan to kill that person, and be darn sure you life is in immediate danger or you will be the one going to jail for murder. Pepper spray is a far better option, especially with how restrictive the law is on weapons.