a small pack with only 2 small docks and a single attachment point. while wearing the pack you have increased climbing stamina. sacrifice inventory space for more efficient climbing
Visually it could feature harnesses, pitons, or coiled ropes, implying that you are using climbing gear to scale wall more effectively.
of course… some tweaks to climbing would have to precede this so that it would no longer be possible to accidentally rip your backpack from your back while trying to climb a wall
I don’t think the reward is enough here. If you’re wearing that climbing backpack and sacrificing that much storage, you should be goddamn spiderman. I think you should have near infinite stamina, and increased muscular power so you can fling yourself with much more power than you put in.
Instead of an item like this that provides passive buffs from just wearing it isn’t the kind of thing I want in ATT. Instead of just being a passive buff that implies you are using climbing gear, I wanna actually use the climbing gear. Of course rope physics would not work well, so climbing picks or axes might be better.