Stainless Steel is not stain proof and a will stain if not properly maintained. Knives made of high carbon steel are even more susceptible to rust and corrosion. Always keep your knife clean and lubricated to shield it from rust and corrosion. If you use your knife to cut or prepare your food, you should make sure to use a food safe lubricant (FrogLube for example) so that you do not ingest harmful chemicals. 

Improper use of the knife can lead to a dull edge or a damaged blade. The uses mentioned in the section above are only a few of the common improper uses. However, cutting on the wrong surface can also cause damage to your knife. Hard surfaces such as a metal table, glass, marble or stone can quickly dull a sharp blade and should never be used as a cutting surface. It is always better to use a proper cutting board (wood or plastic) or to choose a soft surface to cut on.

A screwdriver, or a chisel (despite the grind), or a pry-bar, or a bottle/can opener. Your knife also shouldn't be used to cut through metal such as soda/beer cans, food cans, wire etc. There are specific tools for these tasks that are better suited and won't be damaged in the process. It doesn't hurt to carry a multi-tool such as a small Swiss Army knife or a Leatherman to tackle tasks your knife shouldn't be doing.