Caution can be healthy. But for a Berserker, of what worth is your own health if it means turning your opponent into a large red stain?
Death Wish is a 20-point Fury talent that increases physical damage dealt by 20% but increases all damage taken by 5%. It also grants immunity to [Fear] effects, and lasts for 30 seconds.
A DPS warrior's already fairly high damage is boosted to become VERY high. This ability is also somewhat useful for soloing, since the increased kill rate will actually mean you take less damage from each mob.
At high level instances, it's sometimes wise to use this even while tanking certain encounters. While it does require that you and your healers have fairly decent equipment, 30 seconds of Fear immunity as well as boosted damage and increased rage generation due to taking more damage can greatly assist you in securing aggro during fights such as The Beast or Onyxia.