Wearing a full set of perspicuous warrior armor, this charm provides 122 AC, 2873 HP, 2881 Mana, 2830 End, 63 to all saves and slightly better stats than shown above. This is on a level 100 warrior who's also equipping a warrior-only primary, Evidently the difference comes from the weapon since without it equipped the stats dropped back to what's shown above. Interesting.
Now, the same charm equipped by another toon with a full set of "class-specific" armor, but MIXED perspicuous, distorted and obscure, gets stats of AC 111, HP 2600, Mana 2806, That toon is not using a class-specific weapon.
So I think:
(1) The weapon affects the stats.
(2) Having not just class-specific but class-specific of the same "line" is needed to truly max out at least THIS charm.