During my 1+ year in Vietnam (in combat, in the jungles, etc.) I kept an AF Suvival Knife attached UPSIDE DOWN to my pack's shoulder strap via duct tape until I came across some velcro straps. They were the cat's meow for this purpose. I still keep that same knife (in a replacement sheath) velcro strapped to my pack strap. One piece comes around and across the knife handle itself secuing it with something besides the flimsy leather and snap originally provided. I backpacked much of the Appalachian Trail, the Florida Trail, and made numerous hunting, camping and back-country fishing trips with that knife in that same position and I've never had a problem. I'd recommend a velcro strap at least 3/4" wide - and 1" would be better. They are available at many Internet sights, sporting goods stores and even big box stores like Walmart.