@SavatoIn terms of Strength, Satsuki could lift a Metal Gear with one hand, with ease. We're talking about moving a blade so fast that the friction formed by the blade moving through air superheats the air to such an extent that the outwards expansion causes an explosive burst of energy capable of destroying an entire building. She never even TOUCHED it. The amount of force required to do that is so immense, it makes juggling metal gears look like a hat trick by comparison.
Kamui does drain the strength of users, but Satsuki is able to continue fighting full-tilt for days on end. And hitting her will do only minor harm that is instantly repaired, and that's when you use a weapon of similar destructive power to her own sword strikes. There's a reason she's on the list of people who could beat Doomsday. She's OP as shit, and nearly impossible to defeat by someone unaware of her weakness. The only way to harm her is through the use of attacks that target her internal body, her mind, or her soul.
Yeah, the vibro sword is sturdy. But one of her strikes carries more kinetic energy than being hit by a tank at the speed of sound, concentrated into a super-thin edge. That's probably an underestimate, too.
And yes, life fibers are silly to fight against. Kill La Kill is from the Gurren Lagann school of writing, whereby you try and make the most ridiculously overpowered fights you can.