How to dethaw multiple pieces of steak when not planning to use them all at once
In your specific case I wouldn't eat them after being left unrefrigerated all night due to safety concerns. 

However if I've frozen steak safely and later decided that I want single portion I've found found that a cold chisel normally used for metalworking does a good job of seperating them without defrosting the whole lot. The following image from Wikipedia illustrates what they look like:



I place the meat on a wooden cutting board on it's edge, press the chisel in between where the steaks are joined and give it a quick strike with a hammer. I've tried doing the same with a meat cleaver but the narrow edge on the chisel seems much easier and more effective. 

Presumably the steel used may not be food grade in the usual sense but being tempered I can't see any realistic chance of anything nasty being transferred to the meat, assuming it's clean of course.