Setup -> Utils -> Sounds, you can check which ones you want to keep default.
I think there are dismemberment sounds items in the game, just not in the torishop. So might be added at some point.
This actually got me thinking, I remember seeing a bunch of misc. sound items that were made but not publicly released (or, I assume that's the case).
http://forum.toribash.com/tori_shop_item.php?id=1700
I went through all of em and found this, could this be a pre-existing dismemberment sound or is it something else?