This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 弬 is uncertain. It visually contains 弓 (bow) on the left and a right side that may be a compound of 匚 and 臣, but the original meaning and component function are unclear.
Since the meaning is uncertain, focus on the shape: a bow 弓 beside a container 匚 holding an official 臣. This could suggest a bow stored in a case, but treat the meaning as unknown.
For イ, imagine an eagle (イーグル) perching on the bow: eagle -> イ, and the bow is ready but its purpose is a mystery.