lame, lameness, odd shoe
跛 centers on impaired walking: being lame or having a limp. The 'odd shoe' meaning is a concrete image of that uneven gait, like wearing mismatched shoes.
跛 combines 足 (foot) with 皮, which likely contributes the sound and may relate to the idea of a surface or covering that is uneven, suggesting an impaired foot or gait.
The left side is 足 (foot), and the right side is 皮 (skin/leather). Imagine a foot with a patch of leather tied around it like an odd shoe, making the person walk with a limp.
For ハ, picture a person with a limp laughing 'Ha!' at their own mismatched shoes: Ha -> ハ, and the odd shoe makes the gait uneven.