arrowhead, barb
鏃 centers on the sharp, piercing tip of an arrow: an arrowhead or barb. It is the metal point that does the cutting.
鏃 combines 金 (metal) with 族, which likely contributes the sound and may relate to a cluster or group, but the exact historical role of 族 here is uncertain.
The left side is metal 金, and the right side 族 suggests a family or group. Picture a family of metal arrowheads clustered together, each one sharp and ready.
For ソク, imagine a sock filled with arrowheads: sock -> ソク, and the metal points poke through the fabric.