The most broken thing about 2nd ed for low-level play was combining kits, proficiencies and other bits of rules found in the various splatbooks. The Complete Fighter's is the start, where you can "optionally" turn your non-weapon presidencies into combat buffs. Some of the late 2nd ed Forgotten Realms material also got pretty high powered, especially when compared to the earlier stuff. The Complete Priest's Handbook vs. Faiths and Avatars of the Realms is like a drag race between a Volkswagon Beetle and a Ferrari.