fetters
紲 centers on physical restraints that bind or tie, specifically fetters used to shackle limbs.
紲 combines 糸 (thread) with 世, which likely contributes the sound. The thread component suggests binding or tying, consistent with the meaning of fetters.
The left side is thread 糸, and the right side 世 looks like a leg shackled with a crossbar. Picture strong threads twisted into ropes that bind the ankles like fetters.
For セツ, imagine a prisoner in fetters trying to break free, but the ropes are so tight they make a sharp 'sets' sound as they cut into the skin: sets -> セツ.