decide, determine, archery glove
夬 centers on the act of making a clear, decisive choice or judgment. The specific meaning 'archery glove' is a rare, concrete application, possibly related to the decisive release of an arrow.
The historical origin of 夬 is uncertain. It may have originally depicted a hand holding an object, possibly related to archery or division, but the exact development is unclear.
The shape looks like a person 大 with a small mark at the top, as if making a decisive gesture. Think of an umpire calling a decision: the raised arm signals the final call.
For カイ, imagine a decisive leader named Kai who makes all the tough calls: Kai -> カイ, and his judgment is final.
guai (hexagram 43 of the I Ching: break-through)