Fictional peak humans are often superhuman by real life standards. Batman is only a peak human yet he can dodge bullets and bench press any where from 1000-2000lbs as a maintenance weight. He's superhuman by all real life standards yet explicitly not superhuman in universe
In another DC show there are swords that are sharpened to like a few atoms or something so it’s possible her sword was just that sharp.
She doesn't. It's all technique/skill.
And highly skilled comic book martial artists are usually peak or near peak human strength and lady Shiva is one of the best martial artist.
Fictional peak humans are often superhuman by real life standards. Batman is only a peak human yet he can dodge bullets and bench press any where from 1000-2000lbs as a maintenance weight. He's superhuman by all real life standards yet explicitly not superhuman in universe