Reeeeally now? That's quite possible. If I wanted to know the exact health of a creature, I always just nuked it because, as you say, with physical attacks it shows the full damage of the last hit rather than how much damage you actually did before the mobs HP reached zero.
Buuuut, I do indeed recall that I once did a number of tests trying to find out the health of creatures by smacking them with a sword, and found that the same creatures sometimes had more health than other times. I assumed it was just the regeneration during the time it took me to kill them. Never thought it might depend on the bodyparts hit.
If this is true, it would mean a greater use for the Aim-At stanzas! I'll have to investigate this at once!
Edit - Well, I tried a few beasties so far but didn't yet find any evidence of such an effect. So if you can get a definite example of it, that would be nice
