I have a 34 year old Passier Hannover dressage saddle, and it wasn't treated the best or in the best condition when I bought it. I cleaned it well with saddle soap, took some metal polish to all the screws and metal rigging, and then spent two weeks oiling it with warm oil. My saddle flaps are so supple, they are the envy of my barn.
I promise you, take neatsfoot oil or compound, warm it up in the sun or stick the container in some hot water over the stove. You want that oil WARM. And just pour it on the saddle and just rub it in with a soft cloth. You can watch that leather suck it up. And you keep applying warm oil until it won't absorb any more, wipe off the excess, and buff that baby to a shine. It WILL darken the leather, but your leather with be butter soft.
With bridles and reins, at my barn we poured neatsfoot oil in a 5 gallon bucket, left it in the sun to warm up, and we just dip the bridles completely in the warm oil (be careful of the blingy brow bands, you don't want oil in the jewels, just dip your fingers in and rub the back of the bands) and let them drip dry over the bucket. If they need it, redip them. When they stop absorbing oil, wipe off the excess, buff to a shine. It has made some bridles supple in one session. Sometimes, you may need to redip, but O M G it is worth it for how nice the leather becomes.
You can't forget, leather is animal skin. And like human skin, you have to keep it moist and conditioned. Most horse tack is made of cow hide. Some people might custom make it with horse hide, but usually it is cow. Oil is the best way to care for leather. Saddle soap is a cleaner, and will dry the leather out. Beeswax is just a covering protectant. Oil is how you take care of leather though. Guaranteed.
Think of it not as a failure but as a success in how not to do it.
Don't look in a horses mouth for a gift.