Can you be charged with felonious assault when no one was injured. And only a verbal threat was made?
Do you mean battery instead of assault?
Here is the statute on battery and you can see that it is still felony charge if the conduct did not result in actual harm if it in fact created the risk of substantial harm to the victim:
940.19 Battery; substantial battery; aggravated battery.
(1) Whoever causes bodily harm to another by an act done
with intent to cause bodily harm to that person or another without
the consent of the person so harmed is guilty of a Class A misdemeanor.
(2) Whoever causes substantial bodily harm to another by an
act done with intent to cause bodily harm to that person or another
is guilty of a Class I felony.
(4) Whoever causes great bodily harm to another by an act
done with intent to cause bodily harm to that person or another is
guilty of a Class H felony.
(5) Whoever causes great bodily harm to another by an act
done with intent to cause great bodily harm to that person or
another is guilty of a Class E felony.
(6) Whoever intentionally causes bodily harm to another by
conduct that creates a substantial risk of great bodily harm is guilty
of a Class H felony.
Here is a link to the criminal code regarding violence to the person:
Criminal Defense Attorney
I'm a little unsure about the answer that was posted. You can't be charged with a felony "assault" if there was no harm to someone. The act of making verbal threats to a person, as you described in your question, may be a misdemeanor crime of disorderly conduct. That conduct is not a felony.
The attorney above is right -- in re-reading the statute actual harm (although not great harm) is a required element.
Revisiting this issue -- I see that my first answer was somewhat correct -- Wisconsin Statute, Section 939.32 is entitled "attempt" and states, "...Whoever attempts to commit a felony or crime specified in 940.19...may be fined or imprisoned...."
Therefore, you can indeed be charged with a crime for attempting to commit a battery under Wisconsin Statute, Section 940.19, even if no one was injured.
I say that my answer was "partially" correct because I doubt that a "verbal threat" could contitute an "attempt."