wouldn't an easier way to describe a 'death effect' be: whatever is affected by the spell
Death Ward? ("The subject is immune to all death spells and magical death effects. This spell does not protect against other sorts of attacks, such as hit point loss, poison, petrification, or other effects
even if they might be lethal.")
btw, i recently made a list of all the spell with descriptors here:
http://enworld.cyberstreet.com/showthread.php?s=&postid=446369#post446369
so here's all the spells with the 'Death' descriptor:
Circle of Death - Sor/Wiz 6
Death Knell - Clr 2, Death 2 (also Evil)
Destruction - Clr 7, Death 7
Finger of Death - Drd 8, Sor/Wiz 7
Power Word, Kill - Sor/Wiz 9, War 9
Slay Living - Clr 5, Death 5
Wail of the Banshee - Death 9, Sor/Wiz 9 (also Sonic)
and, of course, arrows of slaying and the Death domain ability
are clearly defined as 'death effects'