[quote=@Kal-El]
Because of his intricate knowledge of the Accelerator's skills, Amata can bypass Accelerator's Redirection. Amata can hit Accelerator by pulling back his attack right before it is redirected by Accelerator's AIM field, because it simply changes the direction of the vector towards its opposite, as such anything that is coming towards Accelerator will be redirected back in the opposite direction. With this method, Amata can use his "Counter" to retract his fist the moment before it makes contact with Accelerator's AIM field, so the Redirection instead pulls it towards Accelerator. 

^ This is what I meant. Basically the shield redirects vectors the opposite direction. So basically if you pull back when the Vector attempts to redirect then it will pull your fist towards the user of the Vector Field instead of push away.
[/quote]

That flaw doesn't exist in Nathanial's shield, because instead of reversing the direction of the object, Nathanial's shield stops them in place. It would be kinda awkward if someone tossed something at him for him to catch, and he accidentally threw it back at their face. This of course means that you could throw a spell grenade at him and it would stick to him, but it would have to be a spell that effects his mind and not just an explosion.