I've never seen it like that though, because with a lich you have no choice. You kill him, he loses a con. With an ap, it is your choice as a player whether to:
- put the weapon to use, by saccing it at a better time (which runs the risk of another ap getting it)
- saccing it early in the ghost state, which doesn't kill the ap
- making sure the guy dies again as he unghosts.
The latter just isn't my way of playing the game, because it feels vindictive to me.
If liches lost a third of a con when their phylacteries were sacced, would you sac one each time a lich unghosts because it is a drawback? I'd still feel bad doing that.