While the arm this spell grants cannot be used to attack, it can be used to extend the reach of Malediction-based abilities without the range penalties. This spell is occasionally used by disabled wizards when they need a hand. It's also used by bound wizards to untie themselves.

Spectral Hand [36] 
    DR 20 [20] 
        Hardened 4 [+80%] 
        Only vs. Non-magical Physical Attacks [-40%] 
        Partial (Spectral Hand) [-80%] 
    Extra Arm [16] 
        Extra-Flexible [+50%] 
        Long 1 [+100%] 
        Cosmic (Not Attached to Body; Hand Only) [+50%] 
            Appears as a ghostly, disembodied hand 
        No Physical Attack [-50%] 
        Weak (1/4 ST) [-50%] 
    Terminal Condition [-20%] 
        Taking damage from the spectral hand 
    Magical [-10%] 
    Spell Components [-10%] 
        Must say "hand" in Latin 
Levels 2+ [+10/level] 
    Increase Long on Extra Arm by 1 level [+100%]