So it must happen a lot in Ohio that people sneak guns in others pockets to the point their law makers wrote the law that way...
I'm having a hard time with that
It is simply a way of illustrating the meaning of "knowingly" to a non-lawyer.
The Ohio legislature added a mens rea requirement to the statute, and they did so through the common law concept of "knowingly." They weren't necessarily concerned with people slipping guns into other people's pockets, but they wanted to limit conviction under the law to those who knew they had a weapon while on the premises. It's a legal concept.
For example, speeding is generally a strict liability crime - whether or not you knew how fast you were going (e.g., your speedometer was broken), you get a ticket if you are going faster than the legal speed limit.
"Knowingly" does not mean you know you are committing a crime - it simply means you acted voluntarily and intentionally.
Under the Ohio law the state need only show that:
1. The sign was conspicuous; and
2. you knowingly possessed a weapon on the premises.
If the mens rea element was eliminated, then it would only be necessary to show that there was a conspicuous sigh and you were in possession of weapon, regardless of how you came to be in possession of a weapon.
Remember, the state has the burden of proof in a criminal matter. If they can't show either element, then you can't be convicted. The "knowingly" element is most shown by circumstantial evidence because seldom is there direct evidence of a person's mens rea.