You misunderstood. Ares gave her a lasso that channeled Zeus's lighting. But she apparently discarded it along with the superpowers Ares gave her. It's not 100% clear though since it's not elaborated on. Her new lasso she apparently created could electrocute things, but apparently wasn't the actual lasso Ares gave her since the one Ares gave her was cursed to make her angry every time she used it.
It's not really clear if that lasso was even a physical object or purely a magical construct. It's still a "lasso of lightning" though.
Fun fact: Black Alice once copied it!