weight, plumb bob, sinker, spindle
錘 centers on a heavy object used to pull something down or keep it steady: a weight, plumb bob, or sinker. The spindle sense is a related tool that uses a weighted piece for spinning.
錘 combines 金 (metal) with 垂, which likely contributes both sound and the idea of hanging down or suspending, as a weight hangs from a line.
The left side is metal 金, and the right side 垂 looks like something hanging down. Picture a metal weight dangling from a string, pulling it straight like a plumb bob.
For スイ, imagine a heavy metal weight swinging on a chain: swing -> スイ, and the weight pulls the chain taut.
counter for spindles
weight (of a fishing net)
spindle
idle spindles
counterweight; counterpoise
muscle spindle
spindle
spindle-shaped
spindle base
falling weight; drop-weight (e.g. test, impact strength)
plumb bob
spindle-shaped; fusiform
spindle shaped
rainbow runner (Elagatis bipinnulata); rainbow yellowtail; Spanish jack; Hawaiian salmon