It could be the standard deal falling under the heading of, 'misleading or blatantly incorrect' description.

(Not at you, at the person that wrote the descriptions.)
I have NEVER heard staff and wand attacks called 'Magical Projectiles' prior to this skill. Projectiles, Attacks, and when a skill doesn't affect both arrows and wand/staff hits, it'll be arrows that're the only attacks affected, in which case they specify arrows.
There is NO skill that specifically addresses wand/staff hits, and seeing as this skill includes arrows, I see no reason to start. Ranged Attacks would fall under the heading of both.
Magical Projectiles is the name used to refer to magical offensive spells that fire of a projectile that can miss through manual movement on the part of the defender, and do not automatically hit the chest piece.
Either this skill is in need of a description change, or it's broken like Mist Form used to be, one way or the other, and I hope it's broken. The effect sounded unique and interesting. If it's just the description that's wrong, it's overpriced and has a crappy recharge, like Magnetic Aura.