You have some good advice here, but you gotta start with what you have. If the leather is so dry as to be brittle and maybe crack a little on the surface, then anything you do will only last for a short while.
I've always hated the stink of Ballistol, but a lot of guys swear by it. I use a lot of beeswax, but not as a leather lube or preservative because it will not last.
When working with cowhide, such as a gunbelt or a cartridge box, Neatsfoot is OK if only lightly used. Yeah...silicon is the leatherworkers bad guy, so be careful during selection. In fact, ANYTHING you put on your leather should be put on lightly. That's only because the length of time you use your stuff will probably be short enough that long term wear will be a minimal problem.
when making shoes for peoples' footsies, I got away from everything off the shelf and began to rely on what another Cordwainer taught me;
Go down to the healthfood store and buy a small bottle of liquid lanolin. If you can stand mutton, although beef will work also, cut a bunch of fat off the raw meat and render it down using a very low heat...no sizzling if you can help it.
Mix them both, started with equal parts, until you get a jelly-like consistency and maybe add a tablespoon of pine oil for a better aroma.
This is referred to as Dubbin ( dubn, dubbn, dubben) by shoemakers, and was a universal ingredient in pre-industrial era.
It'll keep for a long time if sealed, but I am told that the best way to manage it is to avoid making too large a batch.
You might also consider this....off the shelf stuff is not meant to have any "authentic" look or patina. Most leatherwork today, especially factory items, is made to appeal with shine and a gloss or matte finish that is distinctive in appeal to the 21st century eye.
Good luck and post a few pics when yu're done, please.