Past Life: Berserker's Fury - One time per day, you can rage which gives you a +4 Str/+4 Con rage for only 30 seconds.
Let's look at other past life feats.
Bardic Dilettante - Inspire Courage 3 times/rest. Duration is probably greater than 30 seconds if I had to guess. Doesn't increase with levels.
Initiate of the Faith - Healing Word 5 times/rest. Effect increases with caster levels.
Acolyte of Divine Secrets - Avenging Light 5 times/rest. Effect increases with caster levels.
Student of the Sword - BAB equals level and +4 attack 3 times/rest.
Disciple of the Fist - Evasive trance 1 time/rest.
Soldier of the Faith - Divine Favor 3 times/rest. Effect increases with caster levels.
Warrior of the Wild - Barkskin 3 times/rest. Effect increases with caster levels.
Sneak of Shadows - Sneak of Shadows 3 times/rest. Effect increases with character levels.
Arcane Prodigy - Elemental Ray 10 times/rest. Effect increases with caster levels.
Arcane Initiate - Magic Missiles 10 times/rest. Effect increases with caster levels.
Every single other past life feat grants usage of at least 3 times/rest and the effect increases with levels (Bard Past Life Feat doesn't increase by level; Monk and Fighter don't for obvious reasons). Of course, this does not apply to the Monk Past Life which may need to be looked at as well.
How about increasing the uses and duration to Berserker's Fury and Disciple of the Fist so that they may be more viable? Once per day for 30 seconds and the fact that you still get fatigued seems really weak.