I get busted limbs and whatnot fairly regualrly. Any soldiers training wrestling tend to be slamming eachother into stone/wood floors or walls. And I'd watch out for whoever gets hurt the most. They may disguise murders as training accidents. Had a sergeant get injured once a month for three months. first time it was broken ribs, then a broken leg, then a broken wrist. after that three recruits died in three weeks, one of which he openly climed as a kill and didn't care. it was after the third death (he was thrown full force into a wooden wall) I began issuing safety gear (leather armor.) Wrestling injuries dropped exponentially. I didn't see worse then really bad bruising until next year when a wrestler broke his knee.
If nothing else, fatal injuries can be reduced by leather armor so changes to wrestling arent exactly needed yet. As far as proper training, the way the game handles such things is a compromise. The soldiers don't need to waste time getting thier actual weapons and accidents don't happen, and the soldiers don't grow too fond of those cheap billy clubs that were supposed to be stand ins for thier actual weapons. I've seen reports of it happening VERY RARELY however so the possibility is still there outside wrestling, just with the new skidding and such, wrestling has become much more lethal in training.
As it stands, all around training is far as hell from perfect. We'd either end up with soldiers dying regularly off the battlefield, which would piss many people off, or we'd have soldiers trying to carry useless weapons into battle, which would make others pissed. Things that would be needed would be removing the possibility for soldiers to get attached to training weapons, training weapons for all standard combat skills (basically meaning a hammer, mace, sword, axe, spear and maybe knife. Because how the hell do you make a training whip.) While training maces and hammers can be modded in, that only fixes that for the individual.
I personally think wrestlers should go for disabling jointlocks and throw more often, but that also means the AI might have them activly trying to break bones which might defeat the purpose. And the reason I keep mentioning soldiers getting attached to training weapons is in my succession game a soldier got a little too fond of a training pike and carried it into battle instead of his actual combat pike. Almost got him killed.
Bah, i went off on a bit of a rant. My point is, the current system has a means of reducing/eliminating fatal injuries to wrestlers in training with a simple suit of leather armor, and the current training system is a compromise until something better can be figured out. So lets all just enjoy the fact that we can watch our dwarves whack eachother with pointy metal things and not kill eachother by accident somehow.