Question: Astral Shield Strength

[JonBrave]

Now hold up a minute! The in-game & the wiki quote:

A shield of Astral energies forms around the mage. Anyone trying to strike through the shield will have their mind blasted unconscious by the force of the shield. Magic resistance may negate the effect of the shield and allow enemies to strike the mage. The power of the Astral Shield is greater for mages who are highly skilled in Astral magic.

What does Magic resistance may negate the effect of the shield and allow enemies to strike the mage. mean, if not that the shield is stopping attacks in the first place? I don't read that in the way you guys are saying AS functions?