Mo. Rev. Stat. § 565.052: Assault, second degree, penalty.

1. A person commits the offense of assault in the second degree if he or she:

(1) Attempts to kill or knowingly causes or attempts to cause great bodily harm to another person under the influence of sudden passion arising out of adequate cause; or

(2) Attempts to cause or knowingly causes bodily harm to another person by means of a deadly weapon or dangerous instrument; or

(3) Recklessly causes great bodily harm to another person; or

(4) Recklessly causes bodily harm to another person by means of discharge of a firearm.

2. The defendant shall have the burden of injecting the issue of influence of sudden passion arising from adequate cause under subdivision (1) of subsection 1 of this section.

3. The offense of assault in the second degree is a class D felony, unless the victim of such assault is a special victim, as the term "special victim" is defined under section 565.002, in which case it is a class B felony.