Somehow I doubt Frenzied Berserker was really revised at all in Complete Warrior, from its original incarnation within the pages of Masters of the Wild. Frenzied Berserkers, about halfway through the prestige class, become basically immune to damage, vulnerable only to automatic Death or disintegration effects. Considering their high Fortitude save, it's unlikely even Finger of Death, Disintegrate, or Power Word: Kill would even affect a Frenzied Berserker anyway. Basically, the Frenzied Berserker gains the capacity to survive any amount of damage, as long as he gets healed at some point before his Frenzy ends. He could be at negative ten billion hit points and still fight on, until his Frenzy ends and he finally stops ignoring the damage dealt to him. Only thing in 3.5 that makes it less broken is that the Heal spell now has a limit on how many hit points it restores with each casting, so at least in 3.5 there's a slim possibility of a Frenzied Berserker actually dying at some point when their best friend the Cleric doesn't have enough Heal spells available to wipe out all the hundreds upon hundreds of negative hit points the FB suffered while, y'know, single-handedly slaughtering an ancient red dragon when the FB was only around their 12th character level or so.
Okay, so I exaggerate a bit, but not really that much. The Frenzied Berserker may as well be called the Invincible And Unstoppable Immortal Warrior. I suppose you could task Evandariel with making a revised T13K-specific version of the Frenzied Berserker that, y'know, lacks the Deathless Frenzy ability. Then it might be more or less balanced.