I once cut right threw my thumb while slicing some watermelon. I ended up getting 6 stitches at the emergency room. It is said that dull knives are more dangerous than sharp ones, because they are more likely to slip. In a disaster, you will want sharp knives to be able to do tasks properly.
I need to add a knife sharpener to my emergency tool chest, and maybe even the bug out bag. Suburban Survival Blog tested Smith's Diamond Precision Knife Sharpening Kit and posted it here:
It's a well-written and positive review. I am adding it to my Amazon wish list