>>2509287I agree. look at online leather shops or better in person in a shop that sells leather crafting stuff. They will tell you what you need.
If it was me telling you I'd say really for starting off you need a stanley knife or thin sharp utility knife, a few needles, an edge beveler and grove cutter, a stitch marker is good for even hole marking and an awl (I like a 1mm round needle like one as it gives a nice tight hole for 1mm thick thread). I tend to use my multitool pliers if the holes are tight when sewing through thicker leather to pull the needles through.
Id say go waxed cotton for sewing first as its the easiest to use and a block of beeswax to wax your thread if its snagging, just pull the cotton over the block.
The photo is one I just took of 2 sheaths using those tools and some dye for my Enzo Trapper. Both have years of use on them.
