I'll get back to the pouch next time. We've just made a set of gaiters to go over a pair of rigger boots that have alrady been modified by another trader. Decent footwear with grip, that keep your feet dry and look in character are tough to find. Two out of three, no problem, all together, a different story, which is where boot covers or gaiters can come into the equation. Modern boots with grip and waterproofing covered with a leather gaiter that looks more in keeping is one possible solution. It also has the advantage that if you change your boots you can keep the gaiters.
In this particular case the customer had bought a pair of modern rigger boots modified by Battleready but wanted them altered further so they went higher up the leg and coud have a dagger mounted on them. Fastening was to be by straps which went completely round the boot.
For the most part the pattern is based on a slightly conical tube as it's sitting over a fairly rigid boot. The tricky bit of the design is the piece that extends onto the top of the boot and would cover the laces if there were any. The insert is basically a triangle, about 30 degrees, sew onto a wide slit in the bottom front of the gaiter. The front is offset as the closure was to be at the side rather than the back. Straps were 1" wide rather than our usual 3/4" as it's a chunky design and 3/4" looked a little lost. There's also a strap running under the boot to pull the gaiter down onto the boot. If you don't have that then you can get comedy moments when running as the gaiter bounces up and down free of contact with the boots.