Hmm, why not make the Q of the skull for the skull helmet dependent on the previous owner's total LP?
Kill a noob, get a Q3 skull. Kill a veteran player with tons of lp And get a Q100 skull... Giving the skull (and skull-helmet) the name of the previous owner of the skull his name would be cool too.
Taking the skull from a corpse will leave the corpse there, just without skull.. And taking it leaves vandalism/theft scent.