I have friends who rock-climb a lot. One wanted a knife for rope-cutting b/c his friend had a serrated spydie (I deduced this from the description, but not being a knife-nut his description was sadly lacking in relevant details) that worked well. I took a 420HC Arclite, and put reverse-scallop serrations on it, inspired by Kit Carson (& one of the regulars here whose name I can't recall, Will ------). Instead of rising to points, the serrations are a series of round mountains separated by short valleys. A pain in the butt to sharpen, but it doesn't need to get real sharp. Did it with files & a dremel. He says it cuts rope about 3x better than his friend's Spydie, just as Kit designed it to do. Smooth, zips right through. An Arclite is $20 & you can duct-tape it securely anywhere you want. (I also paracord-wrapped the handle, which makes an amazing difference in comfort!)