I think at the end of the crossover just before they were going to fight Krona Thor did know his weakness.
Conversation between Aquaman and Thor.
Thor - "A dire purpose yes. But what an assemblage the finest of two worlds with our unparaleld might and thy noble fire."
Aquaman - "Your might, hm our fire? I might reverse those two after all, Superman and you..."
Thor - "Aye. But i have his measure now and another bout might well hold surprises for the...Kryptonian, you said?"
Kind of suggests he knows his weakness or either he just knows how he works. Not sure.
"Maybe but all i gots to say is it wasnt fan voted thank God "
Yeah. Fan voting is BS isn't it? I really don't like fan voting as I said before when you denied it mattered.
One hammer blow from Thor phased Superman REAL REAL badly.
Almost no one can take that shit and not be hurt. He came back though but as said, they needed the deal.
-AC