Pikal style draw: https://youtu.be/6Sk7B-XXCJY
Your wharncliffe is perfect for this sort is use in the reverse edge grip in style.
Note the light blue Delica. The zip tie head has rounded corners. Still works very, because zip head is mounted on the same side as the clip so it gets maximal pocket contact on the way out. Proper technique as is to put just a little forward pressure on the way up and out during deployment, which again ensures that maximal zip head to clothing contact and gets reliable openings every time.
On the dark blue Manix you see the zip tie head is a little more square which gets marginally more purchase than the rounded head, but everything else is essentially the same.
I even have one mounted on my Pi’kal folder because the metal opener fucks up the inside of my pants rather quickly. Ain’t nobody got time for that.
Although it may look like there’s slack in those zips, they’re on there pretty solid. Proper mounting is key. If you have a vise, use it.
I use pliers to squeeze the edge of the zip head and push it down to get the last click of slack out. If you get more than very minimal movement of the zip head, try the next size zip up or down until you find the sweet spot. You may need to use different sizes ties on different knives because the variable is blade thickness—this is normal.
One thing to keep in mind is the lock you have on your folder. Backlocks like the Delica sometimes experience bounceback where it locks into position and then bounces back out of locked position, obviously very dangerous. This happens when draw the knife out way too aggressively. This does not happen with ball cage and compression locks. Most times the bounceback problem, if your folder experiences it, can be mitigated not only through proper technique but also through playing with loosening or tightening the main adjustment of how the blade sits in the handle.