edge of a blade; cutting edge
Refers to the sharpened edge of a knife, sword, or other bladed tool. Often used in contexts of sharpness, cutting ability, or the physical tip/edge.
The edge of the kitchen knife got chipped.
He sharpened the blade's edge on a whetstone.
I sharpen the kitchen knife's edge every night.
The edge chipped when I cut through the hard bone.
That knife's edge is so sharp you have to be careful handling it.
I pressed the edge against the rope and cut it in one motion.
峰 is the blunt, unsharpened back ridge of a blade, the opposite side from the 刃先 that actually cuts.
Compound of 刃 (ha, 'blade') and 先 (saki, 'tip, point'). The reading はさき is a straightforward combination of the kun'yomi readings of the two kanji.