The military things being due to changes anyway, this might be relatively unimportant:
After reading some unusual comment in the wiki or somewhere, i tried out barracks that consist of a number of 1x1 rooms. I made a 3x3 pattern of rooms (=9, 1 for the armor stand in the middle), separated by internal doors. Tried to visualize that:
WWWWWWW
W_D_D_W
WDWDWDW
W_DAD_W
WDWDWDW
W_D_D_W
WWWWWWW
w = wall, d = door, _ = room, a = armor stand
The rooms actually where stairs to access them from above, doors were forbidden, to avoid concerning what an effect an open door might have. Having a number of dwarves train unarmed skill there resulted in them never being hurt. They gained skill, even in armor user and shield user. So they could become champions even without armor and the risk to hurt their spine/brain something, what otherwise effectively renders them useless. Due to the fact that they seemed also net to get exhausted, they were sparing quite fast... the first completely untrained dwarves were champions in under two seasons.
I know that if the dwarves train unarmed in a normal barracks setup, they usually get those crazy amounts of sparing injuries. They seem no to punch(?) or sth if they are standing on the same field, only trying to wrestle. Especially grabing items from their opponents, because the floors were cluttered with their clothing junk, and even the content of their backpacks was dumped there sometimes.
Using hammers, they again hit each other. Best way to determine that was the red coloring of the floor, only after switching to hammer. It's a little odd what wrestling sparing really does... maybe it will look different in the future anyway, with wrestling being split etc.