Do like me and have all of your migrants duel to the death while naked with adamantine spears. The survivor of the migrant wave gets to join my cadre of elite champions who all 'don't care about anything anymore'.
Barring that, make a bunch of crappy silver and copper weapons and armor with copper or iron if you have a lot of it while your recruits train wrestling. Once your armorsmith hits master start making full plate with caps and chain body armor, and make a stockpile nearby that accepts only armor of that material, and only of high qualities.
Then, once you've got enough to armor your men up station them on the stockpile and tell them to wear chain, they'll put on the caps and body pieces, then tell them to wear plate and they'll put everything else on over it. Then send them to a weapon stockpile that accepts only crappy material low quality weapons and arm them there. Let them spar with that until they've gone legendary then tell them to be unarmed, station them on a stockpile of high quality good material weapons then choose the weapon type you want. With good armor and legendary skill champions will seldom maim each other, though you'd best make a separate barracks area for recruits. While accidentally killing a worthless migrant is no big deal to you it can give your good soldiers bad thoughts, and a berserk legendary champion in full adamantine is not pretty.