well the entire medical AI needs a revamp anyhow
there should really be something simple.. if a leg is wounded it checks if he can still fight and survive.. if yes, he does so.. if no.. he tries to flee.. and so forth.. if he cant flee.. he puts up as best a fight as he can..
in reality.. there are three types here.. the kinds who get wounded beyond beleif but still keep going by sheer will.. and the type who stub a toe and call in sick.. then lastly the kind who can make a careful judgement of their damage. the first type might suicide alot.. but they would certainly do alot of damage to the enemy.. the second type shouldnt be anywhere near the army the third type would be the best.. and could be used effectively in the maner you speak.. sure they lost two legs.. but their arms work.. prop them up by the window and they can snipe quite easily..
so back to that check.. it tests their type if(berzerker == TRUE) doesnt matter how much damage they take.. they fight to the death.. the second.. they get a grey wound they run screaming.. the third would take more judgement calls.. with certain body parts being more important than others and its applied against their weapon. like one weapon might require two arms.. one might require two eyes.. one might require both legs.. so if one of those gets mangled.. or what not.. they have to flee.. if they are bleeding out badly and are likely to die if they continue.. they take off..