In order to help balance certain classes and increase potentially good raid/end reward gear how about making items that have a class and lvl restriction. like a realy nice piece of armour or weapon designed with bonuses or feats to beneft a ceratain class with a minimum class lvl to use and no umd to bypass because its use is not magicall but becase of your experiance and training in a certain class.

examples.
light armor with a +4 dodge ,DD +10, and OL +10 for a build with 10 lvls of rogue NOT a lvl 10 build with 1 splash of rogue

long sword holy +3 but if wielded by a build with 8 or more lvls of paladin the weapon also gains disruption.

You know really cool combos to give to classes to help maintain balance while requiring more that just the slpash of a class to gain all the cool benefits.