.... but, isn't the primary purpose and method of operation of Wierd to destroy life?
You could make the same argument for Fireball and almost every other offensive spell. The key is in the mechanism used by the spell.
...[SIZE=+7][SIZE=+3][SIZE=+2]the banshee's mournful cry is said to foretell death. ... she wails outside the family home of the person who is about to die. The person who is about to pass away never hears or sees the banshee, ...[/SIZE][/SIZE][/SIZE]
Phantasm: A phantasm spell creates a mental image that usually only the caster and the subject (or subjects) of the spell can perceive. This impression is totally in the minds of the subjects. It is a personalized mental impression. (It's all in their heads and not a fake picture or something that they actually see.) Third parties viewing or studying the scene don't notice the phantasm.
It's not summoning an undead. In the [/COLOR]d20 SRD it's a Necromancy spell with a verbal component only, so the "wail" in this case originates from the caster.
Fact is that Weird uses illusion to cause extreme, heart-stopping fear, which is different than directly affecting the life force of the target(s). The target(s) may die as a result, or merely suffer some physiological damage and temporary disorientation as a result.[/COLOR] Wail directly attacks life force by emulating the effect of a supernatural creature.