LD1:
Old leather can only be "helped" so much. It has a finite life. A cleansing with saddle soap, light touch up of scuffs with a good dye, and a final work-in of Pecard dressing is about all I do. And about all that's probably doable. For straps, a good soak in PURE neatsfoot oil is often helpful. Get this at shoemakers or saddle shops. The stuff at the hardware is not good.

Best, Kensal