Whenever you're working with a knife or other blade, it's important that it's as sharp as possible. A dull blade is inaccurate, difficult to use, and outright dangerous as well. When you have to apply more force to a blunt blade, you risk having it slip and do damage to yourself and others. That's why it's so important for anyone who regularly works with a bladed edge of any kind to regularly sharpen their tools. A blade sharpener, therefore, is an essential for people of many crafts.
Blade sharpening tools come in a number of forms "" from the simple yet effective rounded file to manual or automatic whetstones, and more modern gadgets that do all the work for you, there is no excuse to work with dull blade. Why take the risk of bodily harm and go to the extra effort of trying to use a dull blade when you don't have to?
Good blade sharpeners can save hours of work, both in time you'd lose trying to work with a blade that isn't at its optimal sharpness, and in the time it would take to send them off for sharpening "" it isn't a difficult job to do yourself, and with a little practice you'll save time and money that you would have spent on either getting a professional to do it for you, or persevering with a tool that was never going to work as well as it should have.
The frustration of a dull blade is easily solved with a blade sharpener and a little elbow grease, so why keep working with a sub-standard tool when the solution is so close at hand. Regain your ease of use, safety and patience quickly and painlessly with a good sharpening tool and get back to work with confidence and much less worry and hassle over tools that are making your life harder instead of easier.