A portable tool sharpener adapted for mounting on a rail such as may be found on various weapons includes a sharpener body in which a plurality of sharpening tools are mounted and a rail-mounting base pivotally mounted to the sharpener body to allow the body to moved selectively to a closed and open position, wherein the rail-mounting base is releasably engageable with a rail mounted on a weapon, a handle or a fixed pad.

A knife detecting and sharpening system can be installed in a machine base of a splitting machine and adjacent to a band knife, which is an annular loop and is driven by two knife-driving wheels, and adjacent to a wheel shaft of one of the two knife-driving wheels. The system is controlled by a computer of the splitting machine and comprises a resistance detector, connected to the wheel shaft and electrically connected to the computer, and an electric sharpening device, which is mounted inside the machine base and is controlled by the computer to sharpen the band knife's blade, to be withdrawn from the band knife, and to automatically clean dust generated during sharpening the blade. The resistance detector detects a resistance during sharpening and transmits it to the computer, which can control the electric sharpening device operating a sharpening mode or a stop-sharpening mode based on the resistance.