to limp, walking, in motion
蹡 centers on impaired or uneven movement: limping, walking unsteadily, or being in motion with a halting quality.
蹡 combines 足 (foot) with 將, which likely contributes the sound. The character expresses limping or unsteady walking through the foot radical.
The foot radical 足 beside 將 suggests a foot that is not moving smoothly. Picture a general (將) trying to march but limping because of a bad foot.
For ショウ, imagine a limping general giving a show of bravado: show -> ショウ, but his foot betrays him.