Would twilight knife trigger correctly when set to trigger from a Spite spell ?
You can have only one spite spell in effect at a time; if you cast this spell a second time, the previous spell effect ends.
The knife uses your base attack bonus modified by either your Intelligence or Charisma bonus (whichever is higher) when making this attack. Unless you specifically will it to do otherwise, or it proves impossible to do so, the knife always maneuvers itself so that it can flank your opponent before making the attack. The knife deals 1d4 points of force damage on a successful hit and has the same threat range and critical multipliers as a normal dagger. In addition, if the target is denied a Dexterity bonus to AC or the knife flanks the target, the knife can make sneak attacks as a rogue, inflicting an extra 1d6 points of force damage per four caster levels on a successful attack.
A twilight knife cannot be attacked or harmed by physical attacks, but dispel magic, disintegrate, a sphere of annihilation, or a rod of cancellation affects it. A twilight knife's AC against touch attacks is 12 (10 + size bonus for Tiny object) plus your Dexterity modifier.
If an attacked creature has spell resistance, you make a caster level check (1d20 + caster level) against that spell resistance the first time the twilight knife strikes it. If the knife is successfully resisted, the spell is dispelled. If not, the weapon has its normal full effect on that creature for the duration of the spell.
Its the wording about the target of the spite needing to be a valid target for the triggered spell. twilight knife wouldn't exactly target your attacker. Although maybe that's not important as it dosen't say the spell needs to target the creature ?