I did compare it but ill make it easier for you to read. Heart of Praixic fire: has a faster cool down during radiance. heavy weapon ammo, and fusion rifle ammo Armamentarium: get's 2 grenades, heavy ammo, and special ammo We already have the 2 grenade perk and now thanks to that chest piece if your lucky enough to get it you can throw more grenades then they can dream of while in your super. http://destiny.wiki.fextralife.com/Heart+of+the+Praxic+Fire http://destiny.wiki.fextralife.com/The+Armamentarium