Magic lasso as a cutting wire
The lasso is already infinitely long depending on the will of its wielder, I don't see why it couldn't be infinitely thick or thin as well. And since it is infinitely strong too that means the lasso would make the perfect cutting wire for just about anything.
It is a little cruel to use it like this I guess, but I don't think it's all that much worse than a sword. Plus it just makes sense. This way, Diana wouldn't need to leave her most powerful and iconic weapon idle at her hip when going up against villains that warrant a cutting blade.
On the other hand... maybe it'd be interesting to lean into the irony of turning a weapon meant to avoid bloodshed into something which excels at doing exactly that. Say on of the villains obtains the lasso, and they innovate a new usage for it?
The way the Diana uses a cutting lasso doesn't have to look the same as how her villain uses it either. Someone like Circe might favor turning the lasso into spiderweb trap that cuts (or maybe even dismembers) anyone who walks into it, but Diana might prefer to alternate the lasso's width to maneuver and cut as-needed within the battle, looking much more like a ribbon dancer than a spider.