Hi Shawn02, the black coating on the blade is what Benchmade calls BT2. It is a black Teflon based polymer which aids in providing corrosion resistance and gives it an overall stealthy appearance.
Depending on how much you use the knife, it will eventually wear and it can scratch if you cut through, hit or rub abrasive material. If you're not careful while sharpening your knife, you can scratch it. Carrying the knife in your pocket along with keys, coins or other hard objects can scuff the finish as well.
Some people don't like black coatings on blades because when the blade gets scratched, it makes the knife look crappy. If you're the type that enjoys using your knives regardless of scratches or scuffs it really doesn't matter, but there are people who like to admire their knives for a while and try to maintain the "new" appearance. Personally, I think there are more knife enthusiasts out there who dislike blade coatings than those who like them.
My personal preference is a satin finish or stonewash finish, but I do own knives with blade coatings and don't mind using them. Using a knife is the only way to really appreciate it's quality, so scratches and scuffs don't bother me. They simply give the knife "character."
