bow case, scabbard, sheathe
弢 centers on a protective covering for a bow: a bow case, scabbard, or the act of sheathing a bow.
弢 combines 弓 (bow) with a right component that likely contributed both sound and the idea of covering or wrapping. The exact historical development of the right side is uncertain.
The left side 弓 is a bow. Picture the right side as a wrapping cloth draped over the bow, like a protective case or scabbard.
For トウ, imagine sliding a bow into its case with a soft toe-like push: toe -> トウ, and the bow is sheathed.