This Secupro Merak has had rather a lot of design thought put into it. It's a utility knife by German manufacturer Martor, who put safety top-of-mind.

-To deploy the spring-loaded blade, you squeeze the trigger. Once you complete the cut, even if you still have the trigger squeezed, the blade automatically retracts, driven by a lack of pressure. There are two different lanyard connection points, and a safety that locks the trigger, in case you're storing this in a pocket.

The blade deploys just deep enough to cut through two layers of corrugated cardboard. Furthermore, the angle of the handle is such that you can register the blade against the top of the box and prevent scraping it with your fingers.

Even the blade changing process has been carefully considered. Once you open the blade compartment, the cutting edge of the blade is not exposed, and furthermore the blade is held in place by a magnet; this makes it impossible for the blade to fall out or for you to accidentally cut yourself.

Here's a demo of how it all works:

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The tool is sold through industrial channels, not consumer retail ones, and goes for $22.