I'm not overly convinced tbh, your character activated the Hyperarmour as a last ditch effort after making a mistake, I don't really see how he can then compensate for his momentum and the fact that he's mid-jump. That's also not really what you've said, your character has immediately transitioned into a grapple upon landing. The shield lasts 0.5 seconds correct, which in my reckoning would probably carry him to the ground before he could move again. When one lands after jumping they inherently bend their knees slightly to absorb the impact and either step forward or push backwards to cancel out their momentum. I'm not sure your character could do either of those things with the shield active, so presumably he would just fall over. 

I'm going to ask Pollen what they think about the Hyperarmour. If it works as you say then the limitation you've set on it (because it is a very OP ability for low tier) doesn't really limit it in any fashion, as your character can just sprint forward and dive at his opponent, activating it with no cost and immediately entering a grapple.