As a fellow beginner to leatherworking (i've completed 2 sheaths & working on my third) I highly recommend reading the tutorials by G2 & Talfuchre. Granted, they aren't sheaths for a hawk, but the techniques & tools shown in both writeups should get you off to a great start in terms of stitching, finishing, etc. I am quite happy with the results I got from their instructions.
My understanding is that you only need curved needles if you are doing a baseball style stitch or connecting leather edge to edge (not generally applicable to sheathmaking)
My tool list would be as follows (for what it's worth);
sharp, thin-bladed knife for cutting the leather, think paring knife or swiss army knife for blade thickness. That way you aren't wedging the leather apart as much when you're cutting it.
edge beveler
awl
stitching chisel/hole punch (very much worth it for ease of even hole spacing) if you only get 1 get the 3 prong, otherwise get the 4-prong as well
straight needles
wool daubers - pretty much any size ought to work
dye
leather balm
gum tragacanth
are there other tools that will make the process easier & allow you to make your sheath fancier, absolutely, but this should get you in the game at least. Also, don't forget any needed hardware for your sheath, i.e. snaps, rivets, d-rings, etc. Have fun :thumbup: