This is me and the fixed-blade/sheath combo I carry every day, and have done so for several years. I made it myself out of thick cowhide (3/16th" thick), held together with screws and posts. Nothing fancy, just functional and durable.
The upper part of the sheath (belt loop) is made of two pieces of very stiff leather so the sheath doesn't pull up with the knife when I draw it. The sheath holds the knife tightly enough to prevent it from bouncing around or popping out, but loose enough that a firm tug on the knife will clear it from the sheath. I can adjust the tightness of the sheath on the knife by adding or subtracting thin leather spacers where the screws are.
I live in California, where the concealed carry of fixed-blades is illegal. So I designed my sheath specifically to hang below my jacket (I ride a motorcycle everyday, so I wear a jacket every day).
To the OP, what knife are you carrying? Perhaps there are aftermarket sheaths that people can recommend that might work for you.
Aside from that, did I time-warp back to junior high school? What's with all the "I can draw my knife faster than you can draw yours" nonsense

. I imagine a 14 year old practicing their knife draw in a mirror.
I don't get into "quick-draw" knife fights, so being
the fastest draw with a knife isn't really my concern.