I'd like to check this spell for its adherence to guidelines and get some feedback on it.
The Creo Terram guidelines in the corebook state that you add a magnitue to create elaborate shapes. All core spells only create rather formless lumps of matter, other than Conjuring the Mystic Tower (which actually adds three magnitudes for elaborate shape). So shouldn't Sword from the Unseen Scabbard also add a magnitude for creating a "formed" item (making it a CrTe20 spell)? On the other hand it wouldn't need a finesse roll, since - as far as I know - Creo magic always creates a "perfect" specimen of its target.