excel in, surpass, pull out, select
擢 centers on pulling something out from a group, whether physically extracting it or figuratively selecting someone who stands out. The ideas of excelling and surpassing follow naturally from being the one chosen or pulled ahead.
擢 combines 扌 (hand) with 翟, which likely contributes the sound and the idea of pulling out or selecting. The exact historical development of 翟 within this character is uncertain.
The hand 扌 beside 翟 suggests a hand reaching into a group to pull out the best one. Imagine plucking a standout feather from a bird's tail: you select and extract it.
For テキ, imagine a hand pulling out a winning ticket from a box: ticket -> テキ, and the hand selects the one that excels.