I totally didn't just use this image because it was open-domain. Totally not!
3. Practical Everyday Use
Haven't we all had that loose string in our shirt or jacket, that threatened the entire livelihood of our garments? With the heart-pumping stress of sharply pulling down on the loose string, and possibly risking the rapid unraveling of your sweater at the start of your day, wouldn't it be better if you had a unspecified sharp apparatus that could effectively cut such a problem? Along with cutting loose strings, a handy pocket knife can easily help you open envelopes, cardboard boxes, and even hard-to-open plastic packaging.
Look at all those uneven wrinkles and creases! Won't anyone think of the children?!