切れ味 as a noun describes the sharpness of certain things like knives or mental acuteness. Thinking of it as "level" or "degree" of sharpness might help you better understand its use in tandem with 鋭い. Synonyms sharing the sense of sharpness of knives include 切れ and 切れ具合.
You can say 切れ味のいいナイフ or 切れ味の鋭いナイフ, and they pretty much mean the same thing. Redundant? Maybe, but it's nothing out of the ordinary. This occurs in many languages. This kind of construction may not be as common in English, but it does occur. For example, we say "good quality steaks" in a similar manner, but we can also say "good steaks", or even "quality steaks" where quality itself functions as a noun adjunct (or adjective, this is inconclusive and depends on what dictionary you look at).