pull back, restrain
掣 centers on holding something back by force: pulling back, restraining, or checking movement. The two given meanings are close applications of that same controlling action.
掣 combines 制 (control, restrain) with 手 (hand), suggesting the action of restraining or pulling back with the hand. The exact historical development is uncertain, but the component relationship is clear.
The top 制 means control or system, and the bottom 手 is a hand. Picture a hand pulling back on a lever to restrain a machine: 掣 is pulling back to restrain.
For セイ, imagine a hand pulling back a sail (セイ) on a boat to restrain its speed: sail -> セイ, and the hand controls the line.
restraint; restriction; control; check