I'm not sure what you were pointing out, but my point was that other sources of armor do not get separated when it comes to the hardening effect. Unless there's some errata saying otherwise.
My point is that Hardened Armor rather self-evidently, unless you're deliberately trying to misread it for munchkinization, refers solely to the Armor Rating of the Hardened Armor power, not the character's total Armor Rating.
By your interpretation a Main Battle Troll, or even a high-Body Ork (either of whom can easily fit worn Armor Ratings in the 20s), that was possessed by a Force 1 spirit would be able to shrug off anything short of a lucky shot with a Gauss Cannon since they get ItNW (and, therefore, Hardened Armor) as part of being possessed.
Maybe so, but it still has me wondering why "Armor Rating" is capitalized in the description.
Again, that's because Hardened Armor has it's own Armor Rating, which is equal to the rating of the power.
If you have Hardened Armor and you get hit for >=X+1, thus requiring you to actually roll Damage Resistance, then Hardened Armor X adds an Armor Rating of +X/+X. This is the same as adding the Armor Rating of Shields, Helmets, the Adept power Mystic Armor, Being a Troll, Cyberlimb Armor, Bone Lacing, and Form-Fitting Body Armor to the Armor Rating of your main armor.