I love Law, too, it's just, there's no way for him to reasonably win a fight against Blackbeard if Blackbeard drains his powers. Blackbeard survived punches from Whitebeard when he takes double damage from that shit.
Oda is making it clear that Law and Kid are below Luffy because Luffy trains his Haki and Devil Fruit equally now, while Law and Kid are still focused on their Fruits, and need to focus on Haki.
It's not that Law is weak. Blackbeard's just that strong. We still haven't even seen him use his claws and guns in live combat.