How does 殳 resemble a hand holding a tool?
Slight correction, 「殳」 originally depicted a hand 「又」 holding a spear/rod-like weapon/club.


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Forms 1, 3, 5, 6 are all 「殳」. Form 2 is the character 「㱿」. Form 4 is the character 「毀」. Take note of the right hand side of 「㱿」 and 「毀」, which both have 「殳」 as a component.

「殳」 originally depicted a hand 「又」 holding a spear, rod, or club-like weapon, which now looks like 「几」. The original meaning of 「殳」, a kind of weapon, is now written as 「杸」.

As a character component giving a meaning hint, 「殳」 originally had something to do with attacking or hitting. For example,

「擊」 to attack

「殺」 to kill

「毀」 to destroy, ruin

「役」 enslave &gt; labour

「聲」 sound (ears 耳 hearing stone chimes 声 being struck 殳)


Through semantic extension, it was also used as a marker for verb-like words or morphemes, such as

「發」 (to shoot arrows &gt; emit)

「設」 (to establish)



References:

季旭昇《說文新證》
小學堂
國學大師

郭沫若《甲骨文合集》
中國社會科學院考古研究所《殷周金文集成》