The blade of your chef's knife will inevitably have bumps and small grooves. It's all part of the wear and tear of a well-used knife. Small imperfections can be easily smoothed out, but if the blade has chips or large cuts, it may be time to replace the knife. On Western-style knives, the handle is attached to the blade with rivets.
These can corrode or loosen over time, causing the handle to loosen. The resulting blade displacement can cloud your cutting attempts into dangerous imprecision. You should look for a new chef's knife when you realize this. To extend the life of a knife handle, never put it in the dishwasher and keep the wood properly conditioned with oil, and wash and dry it immediately after use.
The lifespan of a kitchen knife depends on a few factors: the blade material, the frequency of use and the maintenance play an important role. However, if treated well, a medium quality knife can last for decades, if not a lifetime. Your knife blade will undoubtedly have some grooves and small marks; all of this is just part of the wear and tear in the kitchen. Small chips or parts that are missing from the cutting edge of your knives are called microcorrosion.
It is often caused by moisture left in the area; it can be any type of moisture left on the blade due to food, so be sure to dry the knife after using or washing it. A professional may be able to smooth out small imperfections, but if a blade receives large chips, it may not be fixable and you will need to replace the knife. Many stainless steel knives can rust, which is usually due to knives being soaked for too long. The stainless element is coated with chrome, which if soaked often enough can begin to deteriorate.
Once this coating has been compromised, the blade is at greater risk of rust formation. Extreme heat, excess moisture, and salt water can cause oxidation, as well as improper drying. A small amount of rust can be removed, but once a knife rusts in a certain location, it is incurable. A cut with a rusty blade is not as clean as is necessary for food preparation and can add impurities.
If you are unsure about using the knife due to the amount of rust, it is recommended to replace it. There are several reasons why the handle may have come off the knife, however, the most likely reason is due to poor quality or old age. The safest option is to replace and invest in a high quality knife and strong structure. A blunt knife can be dangerous, time-consuming, difficult to use, and extremely frustrating, while a sharp, well-sharpened knife will slide through food, making your job much easier.