i believe you need to do the next scripting:
First, add to each unit you want to fist fight:
This addmagazine "Strokefist";this addweapon "Strokefist"
Secondly, create a trigger:
In the condition: Not alive thefirstsoldiersname
and in the action: thefirstsoldiersname setdammage 0;
that trigger will turn the soldier immortal.
create a similar trigger to the second soldier.
i believe this is a temporary solution to your problem