This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
勶 combines 徹 (likely contributing sound and the idea of penetrating or removing) with 力 (strength). The exact historical development is uncertain.
The top part 徹 suggests thoroughness or removal, and the bottom 力 adds strength. Picture using force to completely remove something.
For ケツ, imagine a strong person named Ketsu using force to remove an obstacle: Ketsu -> ケツ.