SCOTUS delivered an object lesson in enumerated powers back during the Clinton Administration. They said that the line item veto was unconstitutional because Congress could not cede its powers to the executive without a Constitutional Amendment.
So if the Legislative is not allowed to cede its own powers, it definitely has no powers to infringe on the enumerated powers of the executive.
One element of Meese's argument is the grant of war-making powers to the President, by Congress.