It's unlikely I'll add specific things, but it's good to hear thoughts. Riffing off the death stuff, accidental death (or severe injury) would be a reason to avoid combat - it could also lead to hostile ghosts/having dead bodies to revive or otherwise handle/etc. (also in line with the possession stuff, haha).
It's also interesting to hear about the beegirls, they're probably a good one for settings to increase the danger of.
There's a mechanic that might be good for combat overall that I've thought about which is room damage - I was initially thinking of it as a thing for champions to harm the manor with, but being a general side effect from combat might work well as well.