Instruct: Classify Amazon reviews into positive or negative sentiment
Query: A very hard but delicate edge

I have owned 2 of the Henckels Twin Ceramx M66 knives for 4 years and find them to be very high performance for softer vegetable slicing and cutting bone out meats. The edges are very hard and prone to microchipping and stains from acidic foods like citrus. I must sharpen on DMT course and fine diamond plates to maintain the edge. Hard rinds and bones are problems that can cause chips from these blades. Again very high performance steels for knife blades.