So, if you have a pet and he becomes seriously injured, he may decide to "fight to the death in a blind rage!"

But then he wins the battle, and recovers.

Well, no matter how recovered he is, even at 100%, he'll still have the "beserk" tag activated, and it never goes away. Ever.

Presumably, this is a bug.

Solution would be: once a monster's HP goes above 25% (or 50%), make them drop out of beserk mode.