After talking with  victor-933 I realized I needed some more reference for the lesser seen parts of GIA armour. Seen here is actually the under-armour that provides artificial muscle support and augmentation; handles medical and life-support; plus serves as an interface point for the standard neural interface system each citizen is issued with at birth.

All other armour systems are layered atop the aug-suit to serve various functions other than just serving as a protective shell. Each constituent component of the aug-suit and upper armor shell responds to the neural interface in the back of each users neck to allow for instant response time.

The undersuit itself actually provides a very adequate defence against shrapnel, un-powered melee weapons, and small arms fire. Not only does it possess an ablative coating to diffuse the energy from plasma shots, but the artificial muscles can contract and harden to stop any edged or pointed weapon from penetrating the layers.

It would suffice to say that the under-armour by its own provides enough protection to thwart nearly any attacker that isn't using military grade weaponry, allowing GIA personnel to subdue any non-military combatants easily and efficiently when not battle ready.