I am still partial to using duct tape to secure an extra knife (fighting blade) to my combat harness. As the OldBaldGuy stated: it does you no good if it isn't on you & I tend to wear my harness after getting to & setting up camp. I still carry my Buck 110 & Leatherman on my belt.
Keep in mind, don't use duct tape unless you either never remove the knife sheath OR you place some paper or something between the harness and the duct tape. The duct tape leaves glue behind and things get messy after that.