An assault refers to an attempt or threat to injure another person, while battery refers to the act of touching someone in a harmful way. This occurs when someone tries to physically strike someone else, or when he acts in a manner that puts the other person in fear of immediate harm. Sometimes, a category of "aggravated" assault or battery is used when the person used a deadly weapon.
In this case, Steven is not liable for attempted battery or battery. This is because he employed his finger, and not a gun or other weapon. Therefore, he lacked the ability to commit the battery, as well as the steps toward the commission of the battery.
However, Steven would be liable for assault, as he placed another in fear of battery. Jacob had reason to fear the possibility of bodily harm. This is because Jacob had every reason to believe that Steven was capable and willing to cause him harm.