Left bow — also
弱's indexing radical (Kangxi #57).
弱 is a reduplication: two bows side by side, each draped with downward strokes (
冫-shape) representing limp, slackened bowstrings. The picture is two unstrung bows hanging weak — the literal source of 'weak, feeble.' Same indexing radical in
弓,
强,
弯,
张.