The Petzl SPATHA Rope Access & Rescue Knife with carabiner hole.
Every rope and rescue tech needs a trusty blade hanging from their belt. What better way than to have the whole blade pivot around your karabiner? No need to detach from it while taking it from your harness or while using it.
Here is Petzl description-
The SPATHA knife is designed to accompany the worker at height during all daily tasks. The blade design allows easy cutting of ropes and cordage. It has a carabiner hole for easily attaching the knife to the harness. It is easy to manipulate with its textured wheel, even when wearing gloves, and can be locked in the open position.