scar, cicatrix, birth-mark
疤 centers on a lasting mark on the skin: a scar, a cicatrix, or a birthmark. All three are visible skin marks that remain after healing or from birth.
疤 combines 疒 (sickness) with 巴, which likely contributes the sound. The character originally referred to a scar or mark left by a wound or disease.
The sickness enclosure 疒 wraps around 巴, like a wound that has healed but left a visible mark. Picture a scar or birthmark that remains after the sickness is gone.
For ハ, imagine a scar that looks like a laughing mouth: ha ha ha! The sound of laughter (ハ) reminds you of the scar's shape.