I know a friend of mine who had his own horse's and rode a lot swore that the best stuff was saddle soap,it's not really a soap it's just a leather conditioner from what I understand it to be,I would think you would want to use something on it because leather is just like wood it can suffer from dry rot.
My Dad had a leather bag that had been forgotten about and it was dry rotten when we found it one day looking for stuff,I would go to a tack shop and see what they recommend if you only knew what people spend on a Saddle you know they are going to want something good to look after it with.
Incase you are not sure what a tack shop is it's a place to buy anything for a house like Saddle's and bit's and other stuff,I can tell you that the one knife sheath my friend had that used saddle soap on his sheath was always really soft and supple.