victory, fast
捷 centers on achieving a result with speed and decisiveness: a swift victory or a fast, agile action.
捷 combines 扌 (hand) with 疌, which likely contributes the sound and the idea of quickness or agility. The exact historical development of 疌 is uncertain.
The hand radical 扌 beside 疌 suggests a hand moving swiftly to seize victory. Picture a hand striking fast like a whip to win.
For ショウ, imagine a swift victory in a show of speed: show -> ショウ, and the hand moves fast to win.