Since is cutting tool period, here's some of my collection. And since I know that not everybody will recognize one of the tools, here's Adam Savage presentation:
Oh yeah the guys at work at Airbus had that exact same tool !
As the guy in the video says, it's used on aircraft.. .though not as much as he says. Well at least not on the A350 and A400M I was working on.
I was doing quality control/inspection on the airframe and we don't use that kind thing for the airframe...for obvious reasons
However safety nuts are used for other ATA systems like typically the mechanical stuff. There are lots of adjustable rods to mount equipment in or around the airframe (in the belly), and although I have left the business a year ago now... IIRC all these rods once adjusted are secured with twisted wire. Even though I was an airframe guy, I was once asked to inspect a twisted wire, I think on a PAX door. Again not my line of business so I had to read up in a hurry about it, and found a standard that explains how to twist the wires... and yes as anything in aircraft, everything is codified...and they tell you the "density" of twists that you must achieve. Just like there are threads per inch on a screw, there are " twists / turns per inch " when you twist a safety wire. I needs to be within X and Y turns per centimeter.
However twisting is a pain so when allowed/possible, ie when you have access to the tip of the screw (not possible on rods of course), then the preferred way is to use a castellated nut with a split/cotter pin. You can put the pin in two different ways, they allow both orientation of the pin. There s a preferred / default way, but the worker is allowed to use an alternate way if it preferes it for whateve reason, like access or just his mood... unless the engineer in the drawing explicitly enforces a particular orientation.