I never played the game. Is this the design of the quiver?
If so it looks like a tube of leather, which would be pretty easy to make.
I have sheets of thin leather that I've used for making belts. I considered holsters but it was too difficult to plan the design. I did make a hat for a DC inspired Scarecrow, the crown of which was practically a tapering tube stitched together a bit like that quiver.
I may be inspired to have a go now. There's the two straps around it as well, which are simple enough apart from forming the buckles and pins.