remove Obsidian Knife

[etehepaladino]

I have a doubt ... the script of the obsidian knife and blessed wooden stake makes me try to extract items from slain monsters, as I do that I'll be able to extract such items and make the obsidian or stake disappear if I can collect the item?

I think it is a function to add the action there, but I do not know where (what line) add or which function is this