and the ratification debates are important, because it gives us the actual meaning, the original intent.
you're right that the WPA does not transfer power, becaue the WPA is unconstitutional. only congress has the power to declare war
"Article I, Section 8, Clause 11 of the U.S. Constitution grants Congress the power to declare war. The President, meanwhile, derives the power to direct the military after a Congressional declaration of war from Article II, Section 2, which names the President Commander-in-Chief of the armed forces. These provisions require cooperation between the President and Congress regarding military affairs, with Congress funding or declaring the operation and the President directing it"
https://www.law.cornell.edu/constitution/articleii
http://tomwoods.com/levin/