easy, smooth, quiet, suave
掞 centers on a state of ease and smoothness: something done without resistance, quiet and suave. The meanings suggest a graceful, effortless quality.
掞 combines 扌 (hand) with 炎 (flame). The exact historical development is uncertain, but it may relate to the idea of handling something with the smoothness of a flame.
A hand (扌) moving like a flame (炎): smooth, easy, and quiet, without resistance.
For エン, imagine a hand moving so smoothly it seems to end (エン) all effort: end -> エン, and the motion is suave and easy.