Why is it an either-or situation? I find both items have a place in a larger kit, as protection is far more important than food or even water, short term.
When you say PSK, a camera bag sounds larger than a pocket kit. How large is the case?
Take a look at the other items in your bag:
Can something be compressed to add a little room?
Can something of lesser importance be eliminated or at least minamized? Cutting back or eliminating any food items might be a first step.
Rather than going from a 2 cell to a 3 cell light, consider a single cell unit.

"There is nothing so frightening as ignorance in action"