Work in Michigan for Wisconsin-based bank. Even though I'm VP and Branch Manager, I was not allowed to discipline an employee for violation of policy (bank policy signed by all employees). This is tied to other improprieties. But my question. . with the bank having eroded my authority (Executive Exemption) does this now qualify me for overtime?

I doubt it. I would imagine that the other duties associated with your position would keep you in the exempt category.