decide, determine, judge
决 centers on reaching a firm conclusion: deciding, determining, or judging something after consideration.
决 is a variant form of 決. The standard form 決 combines 氵 (water) with 夬, which likely contributes the sound and the idea of separating or dividing, suggesting a decisive break like water cutting through. The variant 决 uses 冫 (ice) instead, possibly reinforcing a sense of cold finality.
The left side 冫 suggests ice, and the right side 夬 looks like a hand holding a tool. Picture carving a decision into ice with a sharp tool: once cut, it cannot be changed.
For ケチ, imagine a judge deciding a case and saying 'Ketch!' as a sharp, decisive sound: Ketch -> ケチ, and the decision is final.