It is my understanding that if the police believe a person is in imminent danger they do not need a warrant. This, IIRC, was a decided in a previous SCOTUS case.

Further, if a husband beats the crap out of wife, gets arrested, tells the police that they can’t search for a baseball bat or another weapon that was used, the wife can’t give consent to search the house?

This makes no sense to me. If a person is under arrest, the police would have time to get a warrant to search the hope with no worries of the person either fleeing or causing more harm to the DV victim.