The EvoGrip you linked to appears to have the same sort of scissors as on a Wenger. There’s a separate piece of rigid metal that the moving part of the scissors levers against. That separate piece must have some sort of spring somewhere, but it’s fully enclosed in the hinge of the tool, where it folds into the handle. I’ve had mine for about 30 years or so, and the screw that forms the fulcrum of the scissors now comes loose too easily, but the spring still works fine.