I've had things like that happen occasionally. In my first fort (back in 40d) one of my champion swordsdwarves, armed from head to toe in steel, charged a dragon and lopped its right rear leg off. The leg ended up twenty tiles away in a tree. Meanwhile, the dwarf proceeded to absolutely butcher the dragon, then merrily went back to training.
Oh, and the dragon's leg landed AFTER he was dead.
In another fort I had dwarves hitting goblins so hard that body parts were landing five or six Z-levels above where they severed. Until then I had been unaware body parts could get flung that high.
My favorite instance of military badassery, though, involved a marksdwarf who had come outside after the other soldiers. She was a legendary marksdwarf and one of the founding seven (I gave her military skills at embark because it was a dangerous area.)
During a siege (I'd modded goblins to be more aggressive) she was the last soldier out the door, and consequently she got ambushed and messed up pretty bad before the others could get there to help. Most notably, her left lung got mangled. Most of the goblin squad was decimated, but one straggler got away. As the rest of the military left to take care of another squad, she pulled herself to her feet and clambered up a hill after the goblin who had decided to retreat. Down to her last bolt, she loaded her crossbow and fired.
Now, because I like watching injuries accumulate, and in 40d you didn't get the detailed combat reports, I paused the game after the bolt struck to see where she'd hit him. His brain and left eye were brown (moderately wounded- the equivalent of yellow in v31.x.) She had shot him in the back of the head and the bolt had completely skewered his skull and taken out an eye. Naturally, he fell over, having seizures. A moment later, with half her torso missing, she caught up with him and beat him to death with her crossbow.