It is generally accepted that hand sewn double stitched leather goods are superior to machine sewn. A non-inclusive list of tools is given below. These are basic tools and no power tools are included.
Needles and thread. Straight needles for sewing leather are blunt; a thimble is not needed. Two are required for double stitching. For sewing tight areas, use curved needles.
Knives. A Head knife is a specialty item for working with leather; they can be found on the internet. A utility knife is also required and can be found at any grocery or hardware store.
Hammer(s). Use a hammer without a metal face to strike your metal tools when working leather. Rubber faced hammers are common.
Hole punches. Use a hole-punch made from a good grade of steel.
Awls or thronging chisels. These make a diamond shaped hole.
Burnishing tool(s). The can be made of bone or a synthetic material. Use to burnish the leather, enlarge holes, etc.
Strap cutter. A specialty tool used in making belts. A strap cutter will adjust for width and thickness.
Edge beveller. This tool is used to neaten the edges of cut leather.
Creaser. This tool is used to make lines in the leather. This can be useful for aligning stitches, or the lines can act as part of a decorative element. Standard width and adjustable creasers are both available.
Lacing pony. This tool acts as a third hand to hold pieces of leather together as they are being sewn. Think of a large wooden vise.
Gougers and groovers. Typically, stitches are made in a groove to keep them slightly below the surface of the leather, so they are much less likely to catch on something and come undone. The adjustable stitching groover is used to make a uniform groove along edges for stitching. The freehand groover can cut a groove anywhere on your leather.
Stamps, shaders. These are used to make decorative elements.