I have an EMERSON mini-CQC7, with the wave feature. Just a small notch on top of the blade , no spring, no nothing that could break .
And as soon as the knife is out of my pocket, it's open !
On EMERSON web site , you can see small videos demonstrating the wave system. Amazing !
As far as I know, this system has been inspired from Fred PERRIN , french knifemaker (both EMERSON and SPIDERCO have a version his famous "griffe" (claw) in their catalog).

Alain