Creatures that are Bleeding or covered in a liquid material leave a trail of that material behind them. Would love to see particularly strong melee attacks leave a blood spatter on surfaces.
Dismemberment/Hacking off enemy body parts might be interesting, could see difficulty in balancing between enemy/player interaction. Would the player be in danger of being dismembered as well? I think Qud handles this in a way that fits closest to Soulash's vision (DF's style of dismemberment might be too permanent for it occurring to the player to be fun), where axes and serrated weapons dismember limbs, and there are a variety of way to restore them or... 'obtain' new limbs to compensate. Could see how extra limbs wouldn't necessarily work with the equipment system without a rework.
Flaming Sword and equipment like the Candle Hat should be able to be used like a torch in a pinch as a fire source.