I just had to come back to this one. My earlier response was too all-encompassing. There are, as xbxb reminded us, knife blades intended to be used as screwdriver substitutes. The scout utility knives, the Mil-K818, and the TL-29 are examples. They, and the multi-tools can be handy to have at times but, still, they are poor substitutes for screwdrivers at best.