Upper Body Strength
This is the strength of our upper arms and shoulders, which are about pulling up on holds rather than the ability to hang on a hold. As such for most people, unless you are climbing very steep rock then upper body strength will not be as important as finger strength. If your ability to move across steep rock is held back by not being able to pull through with your shoulders and biceps then this may be a weakness for you. However for some people this might be a technique issue rather than a strength one.