Found a clip of the incident, judge as you like.
youtu.be/lI3jTjiOEHQ (text link as direct upload doesnt seem to work)
After seeing that its pretty obvious he didn't actually have a knife. That doesn't change that fact that what mace mace did was scummy as fuck. Its also pretty obvious that in that situation he was clearly referring to daddy smurf, as he just told him to stop following him then screamed it. The way i see it as blind as you were i would still say that is enough to count it as mace KOSing daddy smurf.