MagnitudeEdit
Due to game mechanics, enchantment magnitude interacts with destruction perks in a counter-intuitive fashion. Elemental damage enchantment perks directly affect the power of their corresponding enchantments (fire damage, etc.). However, while destruction perks increase the damage done when the player uses such a weapon, it does not increase the power of the enchantment its self, as it appears to do in the user interface. Further, when two damage enchantments are present on a weapon, the power of destruction perks affects all of these enchantments -- give it to your follower and the bonus from your destruction perks wont be present.
As an example, with the perks Fire Enchanter(+25%), Augmented Flames(+50%) and 100 enchant skill, adding the frost damage enchantment will produce 25 frost damage. If you add only fire damage, it will do 46. But if you add both, it will be frost 37, fire 46 -- the frost damage magnitude is now being affected by your Augmented Flames perk and the presence of a fire damage enchantment. Now if you add the Frost Enchanter(+25) and Augmented Frost(+50%) perks, it increases both to 69. Add a +32% Potion of Fortify Enchantment and the end result is 81/81.
The same is true for non-elemental damage enchantments, when combined with an elemental damage enchantment. At 100 enchant skill, absorb health will do 20 damage. With Augmented Frost(+50%), frost damage will do 37. But combine them and you'll get absorb health 30, frost damage 37.
This is probably a quirk of Skyrim's game mechanics, perhaps only allowing a single magnitude adjustment per-skill (i.e., Destruction) per-item or just simply per-item