In reality, skulls are just incredibly wimpy at times, and limbs can exert just a wee bit more force than is believable on occasion.
Oh, yes, incredibly wimpy.
Had a vampire char once who slaughtered masses of humanoids and critters. Killed some megabeasts and even refused to die as I wanted him to be killed by bogeymen (actually I was getting bored that nothing could harm him - I even applauded when a person could land a lucky hit against my char...resulting in light and medium bruises).
So I went in the direction of the nearest ocean in the faint hope to be killed by wild sealife (and I wanted some sperm whales in my kill list at least) as I stumbled into a vault. I suddenly changed my plan and went in there - either finding a glorious (un-)death by the hands of the dangerous wardens or some nice loot.
I opened the door and saw nothing but grey floor sprinkled with some brown spots. Went further on as I suddenly saw missed strikes appearing. Looked carefully around and it became apparent that these brown spots were muck assistances. Never seen something like that before. Unfortunately they died too quickly.
Then met some muck soldiers with frosted weapons.
They died even quicker.
I got bored again as it seemed that nothing would let me die in a glorious battle.
Went some floors deeper, pulled some levers and my kill list was rising with muck. I was covered in muck. Muck wherever you looked. Maybe this was the reason that I couldn't see another brown dot moving in my direction.
Surprise struck me when I finally saw some red text across the screen indicating that something hit me and and teared my muscles of my upper body.
I was bleeding...
The first time since some hours.
In a hurry I looked what it was: a judgement of muck. Well, somehow, this appeared appropriate, although the description was anticlimactic:
A flat worm with skinned wings.
Well, if a worm posed the biggest threat in the world who was I to judge...?
I aimed for a swift strike against one of his wings to ground it.
Miss...
It grabbed my left arm with his right wing.
"Okay, flying fishbait, you want to dance..."
I aimed for his right wing in a multiple attack and chose to dodge away afterwards. My high strength and agility should pose no problems.
Miss...
It threw me around.
I slid across the floor.
And my head turned into bloody gore.
Never in my DF-time was I shocked more and filled with pleasure to read:
You're deceased.