What’s fascinating is the prosecutor needs the knife to be legal in order to charge the 3 white officers for illegal arrest and assault. Those 3 officers involvement in the case ended when his legs were shackled and Freddie was placed in the van. Take away those 3 officers and she would be left charging only 3 black officers. Riots may still be going on.
“...or other device for opening/closing the blade.”
This would likely mean that if the knife had a thumb stud, thumb plate or a “bird’s eye” to assist in opening, it would be illegal.