Pat called that model the Key Chain Cutter. He later made another model by the same name that was a friction folder that he had manufactured for him by a company in Japan.
The old style that you have was made as early as 1986, possibly before, and came with a leather sheath. In 1986 they were $35. The text from his catalog said:
"KEY CHAIN CUTTER
Light and small, it is designed to be carried on your key chain. These make great gifts for your wife, because this may be the only protection she has on her at all times. Hand made from 440C stainless steel, the KEY CUTTER is a fist full of protection that is always at your fingertips for everyday cutting jobs or emergencies that you never expect. Custom quality with a hand-sewn leather sheath for only $35.00"
Here is how they look with the sheath.