I make a lot of sword hangers for use in live theatre. I use Craftsman VegTan leather usually, and 7-8 oz weight. Once I have done all the punching/cutting/stamping and dyeing, I rub the leather with Mink Oil made by Kiwi (there are other brands). I rub that into the leather with a rag, then work it in deeper by hand. Not only does it protect the leather, it makes it quite supple.
You could also use a higher grade of leather than Craftsman VegTan; the Oak Leaf is pricey, but has a very soft hand.