韋 is thought to depict a foot (㐄) going around an enclosure (口), originally meaning to go against or oppose. Over time it came to be used for tanned leather, possibly through phonetic loan or semantic extension.
Meaning mnemonic
The bottom 㐄 looks like a stretched hide, and the 口 inside is like a frame for tanning. Picture a skin stretched on a frame to become tanned leather.
Reading mnemonic
For イ, imagine an eagle (イーグル) swooping down to grab a piece of tanned leather: eagle -> イ, and the leather is carried away.
