For the ability to hit both attackers and blockers, this should perhaps cost 3W. It's basically Neck Snap, worse against tutoring, better against graveyard strategies. Cf Vanquish also. (Nonetheless, nice common combatant-removal spell.)

Yes, agreed. Cost changed (could also change to "target attacking" only).

Oh noes noes, it needs to read into its "owner's" library, what if i take control of your creature and attack you with it? does your card go to my library? Otherwise nice card, every set needs to have this kind of removal spell in white.

You're absolutely right, my bad. Fixed.