Whats the legal length for a concealed knife?

Whats the legal length for a unconcealed knife?

If a leo mesures the blade length of a knife to check if its legal how do they mesure? Do they go by the point to the end of the edge? Or do they go from the tip of the blade to the hilt of the knife?

I want to carry a cold steel push dagger but the blade length is like 3 & 3/4 inches but if you measure it from the tip of the blade to the grip its allot longer.

If you carry a unconcealed knife does it have to be on a belt or can it just hang from my key chain regardless of its size?

Are butterfly knifes legal to carry here? I know there kinda cheesy but I have a titanium benchmade & I would like to carry it on occasion.

I was also wondering about asp batons & air tasers. Can these be legally carried & concealed?

Oh I almost forgot to ask about sap gloves, you know regular looking gloves that have steel shot or led in the knuckles. Are these legal to wear around?

Thanks in advance for any information

The laws differ from county to county and sometimes from city to city within a certain county. They also differ from leo to leo and how they're interpreted. Best bet would be go to a local police station or sheriff's department, preferably do not carry the items on your person. These will be the people you will be dealing with if you're in contempt of a law.
I know for a fact the the blade I carry at work, will not fly on the streets of my town, from the tip to the guard is 8 inches, mayors court tossed it out because I forgot about taking it off and leaving it at work, once I demonstrated  I used it to cut hose. He did say next time it would cost me $90 and very possible another knife for his collection.