If charged as a felony, you could be facing a sentence of two to four years in State prison. Regular assault (Penal Code § 240), is always charged as a misdemeanor offense.
The instrument used includes any type of firearm, knife, bat, car, or anything other type of weapon that could produce significant harm to the victim.
In order to prove a charge of assault with a deadly weapon, the prosecutor has to prove beyond a reasonable doubt that you assaulted another person and you used a deadly weapon or force that would likely result in great bodily injury.
An assault charge does not require that you actually make physical contact with or injure the person.