weary, tired
苶 centers on a state of exhaustion and fatigue: being weary or tired.
The exact historical development of 苶 is uncertain. It combines the plant radical 艹 with 尒, but the original semantic or phonetic role of 尒 is unclear.
The grass radical 艹 on top suggests something plant-like, and the lower part 尒 looks like a small, drooping figure. Imagine a wilted plant that has become weary and tired.
For デツ, picture a weary traveler collapsing onto a bed of grass, muttering 'debts' in exhaustion: debts -> デツ, as if the weight of debts makes one tired.