夬

guai

open (through force); release

hand (ji) + arrow (shi)

a hand holding a weapon, symbolizing decisiveness to decide or cut through a problem; its meaning evolved to represent a forceful opening through

冫

bing

决

jue

to decide/determine

be breached,

to burst

ice [bing] + open (guai)

to decide to forcefully open the ice sheet so that the water could burst out

忄

xin

快

kuai

fast, quick;

happy, pleased

heart(xin) + decisive/resolute (guai)

by resolutely pointing a gun toward other's heart everything is solved fast & quickly, which pleased the gun-owner and made everyone happy

土

tu

eart; dust; soil

块

kuai

piece, chunk, lump

soil (tu) + open (guai)

when earth goes through a forceful opening, that creates a lot of chunks of soil