Alan, delete if this is "too much".
Let's get back to the OP's question. He's in the wilderness. Survival situation? What's he need to survive...including making leather items. Well, I doubt if he carried any tanned leather with him. So, what, besides knowledge, does he need. I think he could get by with one, or two, knives. The first should be a sheath knife, 4"-6" long blade. The second should be a pocket knife. The sheath knife can be used for heavy work like building a shelter, constructing traps/snares to supply food...and hides. The pocket knife would be easier for working with food and, possibly, dressing game and hides. Yes, you could do without the pocket knife and use just the sheath knife but it's also insurance in the event of damage or loss of the sheath knife. Yes, both should be carbon steel for ease of sharpening and to use with a rock to start fires. Yep, a smooth river rock (if he's not in N. AR or S. MO) could be use to keep the knives sharp.
Now, he's got his shelter up, leaves and pine needles collected for use as insulating cover at night, fire wood collected and set to light. He has taken time to set some traps/snares. He developed something to hold water, assuming he's smart enough to camp near a water source.
He can sit back and wait for his food supply to come running in. While waiting, he can heat (very dry) rocks in the fire to place in his water in an attempt to kill as many buggers (giardia, etc.) as possible.
Wow, 2 of his snares worked! He's got some squirrels/skunks/rabbits/etc. to eat. With a full belly, he turns his attention to the hides. He's not planning on surviving in the wilderness for too long, so he isn't going to try brain tanning or bark tanning. Besides, he needs something now for foot coverings, head covering, containers for holding cooked food, or whatever. So, he makes sure that all the flesh and fat are removed from the hide. As the hide is drying, he begins stretching/working it in his hands to break/soften the hide. When it's (or they) are done, he can stitch them together with cordage that he's made or strips from extra hides. If he doesn't need the insulation qualities of the fur, he can dry scrap the hair to make "buck skin". This form can be made into containers (bags) and that lace he needed.
So, either one of his knives could be used for his "leather" work.
He must not have had a compass nor a day pack with emergency items. I hope he is wise enough to prepare materials for a signal fire...