seize, spring upon, strike
搏 centers on sudden, forceful physical action: seizing, springing upon, or striking. The common thread is a quick, aggressive movement of the hand.
搏 combines 扌 (hand) with 尃, which likely contributes the sound and the idea of spreading or applying force. The exact historical development of 尃 is uncertain, but the hand radical clearly points to manual action.
The hand radical 扌 beside 尃 suggests a hand spreading out to seize or strike. Imagine a hand springing forward to grab something suddenly.
For ハク, picture a hawk seizing its prey with a sudden strike: hawk -> ハク, and the hand radical represents the hawk's talons.