Weird@55 idea #2
*Plays Jackass the Movie music*

Once upon a time, Arcane magic ruled the world. In the temple of the God of Armour, an armored Archmage (headmaster of the Magocratic empire's primier magic school, which itself had ) mocked Divine Magic everywhere, as well as the gods that provided it. Normally devoted to the protection of brave mortals everywhere, the God of Armour was angered deeply by the archmage. And he invoked a terrible curse upon all mages. The Archmage died the most spectacularly, having his full plate compress and squeeze the life out of the archmage, their in the temple. Several other armored mages suffered a similar fate, but the armor went started for the chest, not crushing every ligament slowly into fine powder, prolonging the sense of agony. The other mages that happened to be armored at the time also did not burst into fire upon death. Druids at the time said "See, we told you so! Those metal armors are the devil!" Sadly, even mages in padded armor died like kobolds as the armor found new and creative ways to crush and/or suffocate them (padded armor inflated into a giant mage-envoloping marshmellow.)

As a result, anytime a mage dons armor, it squeezes the life out of him. To further send the message across the God of armor imposed on all mages a curse that prevented them from recieving the benefits of defense-enhancing cleric magic. Bards apparently did not incur the god's wrath (although they tend to be careful to give extra-proper respect to the God of Armour) Very few wizards and sorcerers survived until word got around that it was THE armor that killed them. Mages are looked now upon as jinxes that are dangerous to be in the same room with (possibly scapegoated for various problems, leading to persucution at some point in the history your campaign world).

God of Armour
Portfolio: Armour, Protection magic, Brave Warriors, Mage-killing character builds, Suffocating Wizards
Alignment: LN
Domains: Law, Protection, War, Destruction
Favored weapon: Spiked guantlet/Shield/armor

....So, would you use this in your campaign?