This is a fun thread to chime in on because of one very strange fortress, my second ever. It consisted of at least 14 full layers of Obsidian in a 7x7 embark with no magma in sight, and a full plain of trees on top, and no idea on my part of how that could have happened in world gen. On top of this, my first fey mood was a Stonecrafter, and about a day later I learned you could make swords from obsidian.
Needless to say, there was a lot of killing power on that map. Ten masterwork-or-close obsidian short swords in each of 64 weapon traps (4x16 down the entry corridor) made a gruesome crimson amalgamation of any siege.
But that was a trivial mess compared to my barracks. It took me a dozen game years to get enough plate armor stockpiled, and in the meantime 42 recruits, 23 swordsdwarves, and 8 champions fell to 'training accidents' in the slaugherhouse 'round the obsidian armor stand. Every migration was committed to the military during this time, and only nine reached Legendary and survived unscathed through the barracks bloodshed and many sieges (not all died in training, naturally). Injuries were swift and usually instantaneously fatal, but it wasn't the recruits dying most of the time, but the Swordsdwarves they were assigned to spar with. I can certainly account that the recruits were far more dangerous to each other or the more skilled dwarves than the latter were to any other creature existing. The champions were barred from sparring while the recruits were hacking each other to bits due to the inconceivable killing of one champion wearing Steel Plate, whom had singlehandedly killed a bronze colossus not a season earlier.
So indeed, Recruits are more dangerous than Champions when sparring.